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- Herausgeber: Biteback Publishing
- Kategorie: Geisteswissenschaft
- Sprache: Englisch
- Veröffentlichungsjahr: 2011
The astonishing story of how the British codebreakers of Bletchley Park cracked the Nazi Enigma cyphers, cutting an estimated two years off the Second World War, never ceases to amaze. No one is better placed to tell that story than Michael Smith, whose number one bestseller Station X was one of the earliest accounts. Using recently released secret files, along with personal interviews with many of the codebreakers themselves, Smith now provides the definitive account of everything that happened at Bletchley Park during the war, from breaking the German, Italian and Japanese codes to creating the world's first electronic computer. The familiar picture of Bletchley Park is of eccentric elderly professors breaking German codes, but in fact the vast majority of people who worked at Bletchley Park were young women. For them and for the young graduates plucked from Britain's best universities who did the bulk of the day-to-day codebreaking, this was truly the time of their lives. The Secrets of Station X tells their story in full, providing an enthralling account of one of the most remarkable British success stories of all time.
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Praise for Michael Smith from former Bletchley Park codebreakers:
‘I’m delighted and astonished by Station X. Michael Smith has caught so well the mixture of nuttiness, angst, hard slog, irritation and euphoria.’ Susan Wenham, Hut 6 cryptographer, breaking German army and Luftwaffe Enigma.
‘Gives a more comprehensive picture of the wartime activities of myself and my colleagues than any other book on Bletchley Park.’ Jimmy Thirsk, Sixta Log Reader analysing German radio communications for Hut 6.
‘A thoroughly enjoyable read and a wonderful reminiscence of times gone by. It brought it all back.’ Pat Wright (née Bing) Hut 8 Type-X Operator, deciphering naval Enigma messages.
‘Michael Smith has made a brilliant job of drawing together an enormous amount of first-hand evidence to produce the first connected account of BP.’ John Herivel, Hut 6 cryptographer and originator of the Herivel Tip, which broke the main Enigma cypher.
‘Wonderfully enjoyable. Station X is very well researched and one of the best books around on Bletchley Park.’ Barbara Eachus (am Abernethy), former secretary to Alistair Denniston, Head of GC&CS, and one of the few surviving members of Captain Ridley’s Shooting Party.
CONTENTS
ACKNOWLEDGEMENTS
I must thank a number of people for their assistance in the writing of this book, most notably Simon Greenish, Kelsey Griffin and the staff and volunteers of the Bletchley Park Trust, who work so hard to keep the memory of the codebreakers alive. I am particularly grateful to the late Keith Batey, and to Mavis Batey, Bill Bonsall, Frank Carter and Brian Oakley for their assistance on technical matters, although I would like to stress that any errors that appear in this book are mine alone. I would also like to thank all the former codebreakers I have interviewed over the past fourteen years and whose memories appear in this book. The work of Bletchley Park codebreakers undoubtedly did much to assist the Allies in winning the war. This book is an unashamed tribute to them and the astonishing organisation that Bletchley Park was.
I thank the Bletchley Park Trust for providing most of the photographs used in this book, Iain Dale and James Stephens at Biteback for their support and their work on this project, Hollie Teague for a superlative piece of editing and Namkwan Cho for a brilliant cover. Thanks are also due to my agent Robert Kirby and to my wife Hayley who, as ever, suffered far more than the author while this book was being written.
Michael Smith, July 2011
CHAPTER 1
CAPTAIN RIDLEY’S SHOOTING PARTY
The sudden increase in activity up at the old Leon estate led to a great deal of excitement in the sleepy Buckinghamshire town of Bletchley in the last few months of 1938. Amid the deteriorating situation in Europe, where war with Hitler and Nazi Germany seemed unavoidable, there was no shortage of suggestions as to why workmen might be so busy laying concrete, installing a new water main, digging in power cables and laying telephone lines to connect the old mansion house at Bletchley Park to Whitehall’s corridors of power.
Then there was that rather odd-looking group of people, mainly middle-aged ‘professor types’ accompanied by surprisingly young women, who arrived at the Park in August 1938. They stayed in local hotels and called themselves ‘Captain Ridley’s Shooting Party’, as if they were there for a weekend in the country. No one in Bletchley was fooled by such a fancy name. Something very odd and very ‘hush-hush’ was going on up at the Park.
The small town of Bletchley had been a tiny hamlet until the arrival of the locomotive turned it into a major railway junction in the mid-nineteenth century. The estate itself had been owned by the Leon family since 1883, when the wealthy city financier Herbert Leon bought it as a country estate. He built a mansion house and used his money and influence to turn himself into a pillar of the local community, first as Liberal Member of Parliament for Buckingham and later as a minor member of the aristocracy. But when he and his wife Fanny died the estate was sold off to a builder who wanted to demolish the mansion and build on the land. The removal of the mansion would certainly have been no loss to Britain’s architectural heritage. It was an ugly mix of mock-Tudor and Gothic styles, built in red brick and dominated on one side by a large copper dome turned green by exposure to the elements. The grounds around the mansion were more pleasant. It looked out over a small lake, rose gardens, a ha-ha and even a maze, all put in place by the Leon family.
As war loomed and Members of Parliament worried over the country’s lack of air defences in the face of increasingly warlike noises from Germany, the mansion was rescued from the demolition ball. A mysterious government official paid the then enormous sum of £6,000 to buy the entire estate and an army of workmen moved in. The story was put about that the mysterious new owner had bought Bletchley Park on behalf of the government to turn it into an air defence training school. The Bletchley District Gazette told its readers that this story had been dismissed out of hand by its sources in Whitehall, but whenever the subject was broached with any of the new arrivals they insisted they were working on Britain’s air defences. Who knew what the truth was? Whatever it might be, it was clearly related to the threat of war, and very, very ‘hush-hush’.
It was in fact far more secret than anyone then living in Bletchley was ever likely to imagine. In June 1938, Bletchley Park had been bought by Admiral Sir Hugh Sinclair, the head of the Secret Intelligence Service – now known as MI6 – to be used as a ‘war station’ for various parts of his organisation, which were scheduled to be evacuated from London in the event of war to remove them from the threat of German bombing. ‘Sinclair bought Bletchley Park out of his own pocket,’ said a former MI6 officer who later worked as the service’s archivist. ‘He could not get any joy out of the War Office or anyone else to provide him with a site so he went and bought it. We know he paid for it, we’re not even sure if he was ever repaid. He died soon afterwards, so he probably wasn’t.’ Sinclair left the estate to his sister Evelyn, which suggests that he had not been paid back, since he could scarcely have left her something he did not own. But he was a wealthy man and he and his sister were extremely close. She shared in the family fortune and had no more need of the money than he did. She had in fact joined the Government Code and Cypher School (GC&CS) before the war began and was one of those sent to Bletchley Park. There is no doubt that she would have been aware of what Sinclair wanted to happen to the estate and she swiftly signed it over to the chief administrative and financial officers of MI6, Captain William Ridley RN and Paymaster-Commander Percy Sykes.
Sinclair certainly planned for Bletchley Park to be the wartime home of the vast bulk of MI6, to keep them safe from German bombs and spies. One group destined to move to the Park at the start of the war mirrored the work of James Bond’s ‘Q’, designing special explosive gadgets for British secret service officers tasked with sabotaging the German war effort. Another included the communications experts who had equipped Britain’s spies abroad with wireless sets to cut the time it took to obtain their intelligence reports and ran the wireless network, together with the ‘decoders’ who unravelled the messages the British secret agents sent back to London. By far the most secretive of the people Sinclair intended to send to Bletchley were the government’s top secret codebreakers, whose existence was virtually unknown to all bar the most senior officials in Whitehall.
The British had been renowned as expert codebreakers since the fourteenth century when King Edward II ordered the seizure of ‘all letters coming from or going to parts beyond the seas’. A royal writ dated 18 December 1324 reminded ports officials that it was part of their duties to ‘make diligent scrutiny of all persons passing from parts beyond the seas to England to stop all letters concerning which sinister suspicions might arise’. By the sixteenth century, the British were infamous for their interception of diplomatic correspondence, with the Venetian Ambassador to Britain complaining that ‘the letters received by me had been taken out of the hands of the courier at Canterbury by the royal officials and opened and read’. Sir Francis Walsingham, Queen Elizabeth I’s spymaster, set up a decyphering department in his London home under the guidance of John Dee, the Queen’s astrologer, to detect Spanish intrigues. Walsingham’s codebreakers foiled the Babington plot, which aimed to replace Elizabeth with Mary Queen of Scots and was the main cause of the latter’s execution.
John Thurloe, who was Oliver Cromwell’s spymaster, placed a ‘Secret Man’ in the Post Office to intercept suspicious mail, a process authorised by Parliament ‘to discover and prevent many dangerous and wicked designs’. During the eighteenth century, the Foreign Office had a ‘Secret Department’ which monitored the correspondence of foreign diplomats based in London and had its own ‘Secret Decyphering Branch’, run by the Reverend Edward Willes, an Oxford don who later became the Bishop of Bath and Wells and who was succeeded by other members of his family. The vast majority of the secret messages they read were Russian, Swedish or French, reflecting Britain’s main enemies at the time, but the branch was closed down in 1847 to save cash with one official complaining that the then incumbent, the bishop’s grandson Francis Willes, had cracked ‘scarcely any’ codes and was merely ‘a fraudulent trickster who leads a life of pleasure and relaxation at his home in Hanger Hill out of sight of the office.’
The First World War and the military use of the new invention of the wireless led to an inevitable resumption of British interception of other countries’ messages. The War Office used the excuse of ‘censorship’ to obtain the diplomatic communications transmitted by relay stations of international telegraph companies based in British territory, setting up a codebreaking operation to decypher the secret messages. The British Army intercepted German military wireless communications with a great deal of success. E. W. B. Gill, one of the Army officers involved in decoding the messages, recalled that ‘the orderly Teutonic mind was especially suited for devising schemes which any child could unravel’. One of the most notable successes for the British cryptanalysts came in December 1916 when the commander of the German Middle East signals operation sent a drunken message to all his operators wishing them a Merry Christmas. With little other activity taking place over the Christmas period, the same isolated and clearly identical message was sent out in six different codes, only one of which, up until that point, the British had managed to break.
The Army codebreaking operation became known as MI1b and was commanded by Major Malcolm Hay, a noted historian and eminent academic. It enjoyed a somewhat fractious relationship with its junior counterpart in the Admiralty, formally the Naval Intelligence Department 25 (NID25) but much better known as Room 40, after the office in the Old Admiralty Buildings in Whitehall that it occupied. Room 40 was set up shortly after the start of the war on the orders of Winston Churchill, then First Lord of the Admiralty. Churchill directed that Sir Alfred Ewing, the Navy’s Director of Education, who had dabbled in codes and cyphers as a hobby before the war, should lead the codebreakers:
An officer should be selected to study all the decoded intercepts, not only current but past, and to compare them continually with what actually took place in order to penetrate the German mind and movements and make reports. The officer selected is for the present to do no other work. I shall be obliged if Sir Alfred Ewing will associate himself continuously with this work.
Ewing set up a series of listening stations around the country, all manned by the Post Office. He also recruited a small number of language experts, firstly from the Naval colleges at Dartmouth and Osborne and then from the universities. One of the first of these naval instructors turned codebreakers was Alastair Denniston, a diminutive Scot known to his colleagues as A.G.D. and by close friends as Liza, who would become the first head of Bletchley Park. But by far the most productive source of codebreakers was the universities. Ewing went back to his old college, King’s, Cambridge, to bring in two Old Etonians: Dillwyn ‘Dilly’ Knox, one of the most brilliant and most eccentric of the codebreakers, and Frank Birch, a talented comic and famous actor, who would later appear in pantomime at the London Palladium as Widow Twanky in Aladdin. Other eminent recruits, almost entirely Old Etonians, included William ‘Nobby’ Clarke, a lawyer whose father had been Solicitor-General and had represented Oscar Wilde during his 1885 trial for gross indecency, and Nigel de Grey, a publisher whose diminutive stature and unassuming nature led the more extrovert Birch to dub him ‘the Dormouse’. It was de Grey who is credited with giving Room 40 its greatest First World War triumph: the decyphering of the so-called Zimmermann Telegram (although it was in fact Knox who initially broke into the cypher). The telegram showed that Germany had asked Mexico to join an alliance against the United States, offering Mexico’s ‘lost territory’ in Texas, New Mexico and Arizona in return, and brought the United States into the war.
There was little or no cooperation between the Army and navy codebreaking departments, with Denniston, who ran Room 40 at the end of the First World War, lamenting the turf war between the two organisations: ‘Looking back over the work of those years, the loss of efficiency to both departments caused originally by mere official jealousy is the most regrettable fact in the development of intelligence based on cryptography.’ The Army and Navy codebreakers did eventually begin to exchange results in 1917, but there remained little love lost.
At the end of the First World War, there were a number of people within Whitehall who were keen to axe the codebreakers as part of a peace dividend. But they were far outnumbered by those anxious not to lose the intelligence that the codebreakers had been producing. The Army and Navy codebreaking operations were amalgamated into a single organisation in 1919. Denniston was given charge of the Government Code and Cypher School (GC&CS), as it was to be known, with a staff of just over fifty employees, around half of whom were actual codebreakers.
‘The public function was “to advise as to the security of codes and cyphers used by all government departments and to assist in their provision”,’ Denniston later recalled. ‘The secret directive was “to study the methods of cypher communications used by foreign powers”.’
The main source of those communications was the international cable companies, who were told to continue to pass over diplomatic telegrams to GC&CS which copied them and returned them within twenty-four hours. ‘Secrecy is essential,’ noted Lord Curzon, the then Foreign Secretary. ‘It must be remembered that the companies who still supply the original messages to us regard the intervention of the government with much suspicion and some ill-will. It is important to leave this part of our activity to the deepest possible obscurity.’ Amid concern that the process could fall apart if any of the telegraph companies chose to object, a clause was inserted into the 1920 Official Secrets Act allowing the Home Secretary to order the companies to hand over the cables to the codebreakers. Two Royal Navy intercept sites at Pembroke in South Wales and Scarborough, Yorkshire, also provided GC&CS with coded wireless messages.
GC&CS came under the control of the Director of Naval Intelligence Admiral Hugh Sinclair, a noted bon-viveur who installed it in London’s fashionable Strand, close to the Savoy Grill, his favourite restaurant. It worked almost entirely on the diplomatic telegrams handed over by the commercial cable companies. The main target countries for the codebreakers were America, France, Japan and Russia, with the last providing what Denniston said was ‘the only real operational intelligence’. When Sinclair was transferred to another post, in 1921, the Admiralty handed GC&CS over to the Foreign Office. The codebreakers moved to Queen’s Gate, Knightsbridge, and were told to forget about military and naval communications and concentrate on decyphering the diplomatic cables, not just of Britain’s enemies, but also of some of its friends. ‘It was a very small organisation for the Treasury had, throughout the negotiations, been insistent on cutting down the expense,’ recalled Nobby Clarke.
The inevitable had happened. There seemed no longer any need to study the communications of a naval and military nature. The Navy and Army of Germany had disappeared, never were they supposed to rise again. To show the extent of the change, in the early days of 1920, the strongest section of the GC&CS was the United States section, to which Knox and Strachey and a number of lesser lights were attached.
Perhaps understandably, the Admiralty saw little reason to fund the collection of diplomatic intelligence, and Britain’s codebreakers were soon placed once more in the hands of the Foreign Office. When Admiral Sinclair was made head of MI6 in 1923, he also took over control of GC&CS, Denniston said. ‘It became in fact an adopted child of the Foreign Office with no family rights and the poor relation of MI6 where peacetime activities left little cash to spare.’
The codebreakers were recruited, as with their MI6 colleagues, from a limited circle of people within the establishment. Joshua ‘Josh’ Cooper, who would become a leading member of Bletchley Park and subsequently its Cold War successor GCHQ, recalled being recruited as a ‘Junior Assistant’ in October 1925 when he was twenty-four.
Like many other recruits, I had heard of the job through a personal introduction – advertisement of posts was at that time unthinkable. In my case introduction came through the family of the novelist Charles Morgan, whose father Sir Charles Morgan of the Southern Railway was an old friend and chief of my father. I was one year down from University of London King’s College with a first in Russian and had found nothing better to do than teach at a preparatory school at Margate. My father was bewailing this at tea with the Morgans one day, and one of Charles’s sisters remarked that she had a friend called Sybil Pugh who worked at a place in Queens Gate where Russian linguists were actually wanted. So in due course I took an entrance exam which included a number of puzzles, such as filling in missing words in a mutilated newspaper article and simple mathematical problems calling for nothing more than arithmetic and a little ingenuity. I wasted a lot of time on these, thinking there must be some catch and rechecking my work and so did not finish the paper. Nevertheless I got top marks. There was also an interview board where I found Denniston, whom I had already met, and for the first time met ‘C’ (Admiral Sinclair) the Director of GC&CS. I do not think this exam was ever repeated but selection continued on a fairly haphazard basis right up to the [Second World] War.
Cooper was set to work on Russian cyphers alongside Ernst Fetterlein, who had been codebreaker to the Tsar, where one of his main jobs was solving British codes, a role that was now reversed. ‘Fetterlein was a devotee of his art,’ one of his former colleagues in the Russian Cabinet Noir recalled.
I was told that once, when he was sent to London with dispatches, he sat morosely through breakfast until suddenly a complete change took place. He beamed, began to laugh and jest, and when one of the embassy officials asked him what the matter was, confessed that he had been worried by an indecypherable word which occurred in one of the English telegrams he had decyphered. Someone had in conversation mentioned the name of a small English castle to which the King had gone to shoot and this was the word in the telegrams which had bothered him.
Fetterlein, who was by then fifty-two, had a large ruby ring given to him by Tsar Nicholas in gratitude for his achievements, which included breaking a German Navy message which enabled the Russian Navy to sink a number of German ships in the Baltic in 1914. This was helpful to Fetterlein’s future employers. The Russians recovered a naval codebook from the light cruiser the Magdeburg, which they passed on to the British.
Fetterlein fled Russia during the Bolshevik takeover in November 1917, later telling William Filby, one of his new British colleagues, that he and his wife narrowly evaded a search of the ship by trigger-happy Bolsheviks. ‘As the top cryptographer in Russia he held the rank of admiral,’ said Filby. ‘His stories of the day the revolution occurred, when workmen stripped him of many decorations and bullets narrowly missed him, were exciting. It is said that the French and the British organisation were anxious to get him and Fetterlein simply sat there and said: “Well gentlemen, who will pay me the most?”’
The British evidently offered the most money. Fetterlein was recruited by Room 40 in June 1918, working on Bolshevik, Georgian and Austrian codes, Filby said.
Fetty, as we addressed him, would arrive precisely at 9.30 and read his Times until ten when he would adjust a pair of thicklensed glasses and look to us expecting work to be given to him. He was a brilliant cryptographer. On book cypher and anything where insight was vital he was quite the best. He was a fine linguist and he would usually get an answer no matter the language.
Josh Cooper already knew Fetterlein, having been introduced to him by one of the teaching staff at King’s College.
His experience and reputation were both great, and I was fortunate to find myself assigned to work with him on Soviet diplomatic, which at that time consisted of book cyphers, mostly one part, re-cyphered with a 1,000-group additive key. He took very little notice of me and left it to an Army officer who had been attached to GC&CS, to explain the problem. Traffic was scanty and it was hard to get adequate depth. It took me some time to realise that almost every group had two meanings. After about six weeks’ work, during which I rubbed holes in the paper with endless corrections, at last I read my first message which was from Moscow to the Soviet representative in Washington and was concerned with repudiation of debts by American states. Later we got much better material from Tehran, where traffic was a great deal heavier and was obtained from the Persian post office by MI6. Hitherto it had been exploited locally by an Army officer resident in Tehran, but now the work was transferred to GC&CS. Later still we got even more voluminous material obtained in the same way from the post office in Peking, and were able to solve for the first time whole additive tables.
Despite Cooper’s problems with the cypher he was put to work on, the amount of Soviet messages continued to increase with the opening of a new Royal Navy intercept site at Flowerdown, near Winchester, an Army site at Chatham and an RAF site at Waddington, in Lincolnshire.
The Russian messages disclosed a concerted attempt to provoke a Bolshevik revolution in Britain in 1920 and repeated attempts to subvert British society throughout the 1920s and 1930s, but this success was a double-edged sword. First in 1920 and then again in 1923 and 1927, the British government used Russian messages broken by the codebreakers as evidence of the communist threat to Britain, leading to changes in Soviet cypher systems that by the late 1920s had all but ended the codebreakers’ success against Russia’s diplomatic cyphers. After the government’s 1927 admission that GC&CS was reading Moscow’s secret messages, the Russians began using the one-time-pad system which, when used properly, was unbreakable.
The codebreakers had little in the way of formal training, Cooper recalled.
The structure of the office was pretty hopeless. It had begun as six Senior Assistants and eighteen Junior Assistants but by the time I joined it was, I think, one Senior Assistant with a responsibility allowance (Denniston), twelve Senior Assistants and twelve Junior Assistants. Supporting staff consisted of a few misemployed typists, some women on MI6 books and, I believe, a few women employed as ‘JAA’ (Junior Assistant’s Assistant). For it was the Treasury’s understanding that Senior Assistants broke new cyphers and Junior Assistants decyphered and translated the texts. Recruitment by personal introduction had produced some very well-connected officers, especially among the seniors. At best they were fine scholar linguists, at worst some of them were, frankly, ‘passengers’.
Very little interest was shown in naval or military messages in the immediate wake of the First World War and responsibility for assessing the value of these was left largely to naval and military intelligence. But in 1924, GC&CS set up a small Naval Section under William ‘Nobby’ Clarke, a veteran of Room 40 and then forty-one years old. It obtained its intercepts from the Scarborough station; from the new Royal Navy site at Flowerdown, which had replaced Pembroke; and from operators on board Royal Navy ships who intercepted foreign naval messages in their spare time. The Army still had its intercept site at Fort Bridgewoods, Chatham and in 1930 a military codebreaking section was formed at GC&CS under the command of Captain John Tiltman. The RAF had set up its own intercept station at Waddington, Lincolnshire, in 1927, but it was not until 1936 that an Air codebreaking section was created in GC&CS with Cooper in charge. Two years later, the RAF intercept site moved from Waddington to Woodhead Hall at Cheadle, in Staffordshire. There were also a number of intercept stations at various sites overseas at the end of the First World War, including Malta, Sarafand in Palestine, Baghdad, and Abbottabad on the North-West Frontier. A Royal Navy intercept station was set up in Hong Kong in 1934 as the threat from Japan became more evident. The messages provided by this network and the international cable companies were augmented by diplomatic and clandestine messages intercepted by a small Metropolitan Police wireless unit based initially in the attic at Scotland Yard and from the mid-1930s in the grounds of the Metropolitan Police Nursing Home at Denmark Hill, south London. The unit, which was controlled by Harold Kenworthy, a Marconi wireless expert, was co-opted by Sinclair to provide GC&CS with both intercepts and technical advice.
By now, Sinclair had moved both the codebreakers and his MI6 staff to a new joint headquarters at 54 Broadway, close to Whitehall and the centre of power. The resurgence of Germany under Adolf Hitler and the Nazis had led to a realisation that war was inevitable and determined efforts were being made to try to break the German cyphers. Cooper recalled that the British codebreakers had almost totally ignored them since the end of the First World War assuming they must be unbreakable:
Another grave fault in the old GC&CS was the tradition, which I found firmly established when I joined, that German cyphers were invincible. Considering what Room 40 had achieved in 1914–18 it seems extraordinary that anyone should believe this, but it was generally assumed that no civilised nation that had once been through the traumatic experience of having its cyphers read would ever allow it to happen again, and that after the wide publicity given to Room 40’s results, together with unfortunate leakages to the Germans during the Peace Conference it would be waste of time to work on German high-grade systems. The result was that for twenty years one man was employed to read the German diplomatic low-grade code traffic which was of no intelligence value whatever.
Germany had indeed learned its lesson from the publication of the Zimmermann Telegram and, during the 1919 Paris Peace Conference, its delegation used the one-time-pad system, blocking British attempts to read its communications with Berlin. It also began looking at the possibility of using cyphers generated by a machine. The publicity given to the success of the British codebreakers during the First World War led a number of nations to adopt machine cyphers, which were seen as more difficult to break. The most famous of these was the Enigma machine. The first British contact with the machine came in 1921, when it was still in development. It was shown to the British military attaché in Berlin, in the hope of persuading the British armed forces to use it.
The German Navy introduced the Enigma machine cypher in 1926 and for a brief period it remained a possibility that both the British and the German armed forces might use it. In 1927, Commander Edward Travis, a member of GC&CS who oversaw the construction and security of British codes and cyphers, asked Hugh Foss, a specialist in machine cyphers, to test the commercially available machine.
The Enigma machine resembled a small typewriter encased in a wooden box. It had a typewriter-style keyboard, set out in the continental QWERTZU manner, which differed slightly from the standard British/American QWERTY keyboard. Above the keyboard, on top of the box, was a lampboard with a series of lights, one for each letter of the alphabet. The operator typed each letter of the plain-text message into the machine. The action of depressing the key sent an electrical current through the machine, which lit up the encyphered letter on the lampboard.
The encypherment mechanism consisted of three or four teethed wheels or rotors which were inserted into the machine. The wheels had twenty-six different electrical contacts on each side, one electrical contact for every letter of the alphabet. Each electrical contact was connected to one of the contacts on the other side of the wheel by internal wiring. The order of these contacts and their wiring was different for each of the three wheels, which could be set at twenty-six different starting positions with any one of the twenty-six contacts at the top. They could also be placed in different orders within the machine to add further difficulties for anyone trying to break the cypher.
The action of depressing each key turned the first wheel one position. When that wheel had moved a set number of times, the second wheel moved round one position, and when the second wheel had turned a set number of times, the third wheel moved round one position. The point at which the next wheel moved was known as ‘the turnover’.
The Enigma machine had two crucial features which Foss realised would help anyone trying to break it. A letter could not be encyphered as itself (so if the operator pressed ‘T’, for example, the only letter that would not light up on the lampboard was ‘T’ itself), and the machine was reciprocal, i.e. if ‘P’ was encyphered as ‘T’, with the machine set at the same position, ‘T’ would be encyphered as ‘P’.
The number of different settings for the commercial machine was put at several million. But Foss determined that while it had a ‘high degree of security’, it could be broken if accurate ‘cribs’ were available. ‘Cribs’ were predictions of possible original plain text, usually standard parts of routine messages, such as situation reports sent out every day. One of the most common was Keine besondere Ereignisse, ‘nothing to report’, which because of its brevity and common usage in situation reports was easy to spot.
Foss later recalled: ‘I wrote a paper entitled “The Reciprocal Enigma” in which I showed how, if the wiring was known, a crib of fifteen letters would give away the identity and setting of the right-hand wheel and how, if the wiring was unknown, a crib of 180 letters would give away the wiring of the right-hand and middle wheels.’
The British decided not to buy the machine, although the RAF used it as the inspiration for a much more secure rotor-based cypher machine known as Type-X which British armed forces used with great success during the Second World War. A year after Foss’s investigation, the German Army began using the Enigma machine and within two years had introduced an enhancement that greatly improved its security.
The Stecker-board was an old-fashioned telephone-style plugboard, which allowed the operator to introduce an additional encypherment, using cables and jacks to connect pairs of letters: ‘B’ to ‘Z’, ‘V’ to ‘L’, etc. This made the machine very much more secure, increasing the variations of encypherment to 159 million million million possible settings and blocking British attempts to read the Wehrmacht systems for around eight years.
The Spanish Civil War brought a flood of operational Enigma messages and on 24 April 1937 Dilly Knox managed to break the basic non-steckered machine supplied by Germany to its Italian and Spanish allies. Shortly afterwards, he began working on the steckered systems used by the Wehrmacht for high-grade communications between Spain and Germany. Knox made some progress, but while he knew that the Stecker-board was what made the Wehrmacht machines more secure, he was unable to decypher any German Enigma messages.
CHAPTER 2
CONFIDENTIAL WORK FOR THE FOREIGN OFFICE
The German annexation of Austria in March 1938 and the subsequent threats to Czechoslovakia made clear that war with Nazi Germany was inevitable. Hitler warned on 30 May 1938 that it was his ‘unalterable will to smash Czechoslovakia by military action in the near future’. British Prime Minister Neville Chamberlain flew to Germany to try to persuade Hitler to modify his demands, but at the same time Britain was preparing for war and on 18 September 1938, the bulk of the Government Code and Cypher School (GC&CS) and a number of sections of MI6 were moved to Bletchley Park as ‘a rehearsal’.
The move was in keeping with the rather genteel atmosphere enjoyed by the codebreakers at Broadway Buildings, the result of Sinclair’s belief that they were fragile characters who needed careful treatment. ‘There had been a tragic case of suicide shortly before I joined,’ recalled Cooper. ‘A man called Fryer threw himself under a train at Sloane Square and “C” had formed the opinion that the work was dangerous and people must not be overstrained.’ No doubt reinforced in these opinions by the eccentricity of many of the codebreakers, Cooper included, Sinclair ordered that they should only work between 10am and 5.30 in the afternoon, with a one-and-a-half hour break for lunch.
Barbara Abernethy joined GC&CS in August 1937 at the age of sixteen. She was fluent in French, German and Flemish and was working at the Foreign Office. When Denniston asked for a new typist, she found herself sent across to Broadway. ‘I was posted over there for a week not knowing what I was doing and told that it was strict secrecy,’ she said. ‘I was there for a week and they apparently approved of me because I was kept on and I stayed there. Life was very civilised in those days, you know, we stopped for tea and it was brought in by messengers. I was very impressed by this, first job I’d ever had and it seemed paradise to me. I thought: “Well, this is the life, isn’t it. Thank God I’m not back in the Foreign Office”.’
The 1938 Bletchley ‘rehearsal’ began on 18 September 1938 and was managed by Captain William Ridley RN, the chief MI6 administrative officer, hence the nickname of ‘Captain Ridley’s Shooting Party’. It involved the Military, Air and Naval Sections of GC&CS, the Enigma research party under Dilly Knox, and a number of sections of MI6. They were to stay at Bletchley for three weeks. Cooper recalled:
We were told that this was just a ‘rehearsal’, as in fact it turned out to be. But we all realised that the international situation was such that the ‘rehearsal’ might well end in a real war with Germany, and probably also with Italy. All personnel of every grade were accommodated in hotels in Bletchley and surrounding towns and villages. The Admiral sent out an excellent chef from London and we all sat down to lunch together at one long table in the house. All this was simply paid for out of MI6 funds. MI6 also provided some cars for transport, but many people used their own cars and gave lifts to others. It fell to my lot to be driven in from Stony Stratford by Knox, who had a remarkable theory that the best way to avoid accidents was to take every cross-road at maximum speed.
The mix of young female secretaries and rather elderly and eccentric male codebreakers, many of whom had worked in Room 40 or its War Office equivalent during the First World War, scandalised the staff of the hotels where they were staying. The head of the Naval Section ‘Nobby’ Clarke, by now fifty-five years old, recalled booking into the Bridge Hotel in Bedford with two male and three very young female colleagues. ‘The men were all in their late fifties and the females somewhat younger,’ Clarke said. ‘Each day to the astonishment to the hotel staff they all went off in a car and did not return until late in the evening. It seems to have been thought that these must be a party of elderly gentlemen with their young women. A chambermaid at the hotel who was complaining of over-work, on being told that times were serious and that she should not complain, said: “It’s alright for you, but some of us have to work.” Little did she realise what these odd people were doing.’
The chef sent in by Sinclair was in fact his favourite chef from the Savoy Grill and the meals were very much haute cuisine. But after a few days of trying to deal with the demands of the some of the more difficult codebreakers, the chef also attempted suicide. Clarke was forced to telephone the Buckinghamshire Chief Constable in an attempt to keep the story out of the papers and ensure that the codebreakers’ presence at Bletchley Park remained secret. ‘Then we learned that Chamberlain had flown to Munich and made an agreement with Hitler,’ Cooper recalled. ‘We all trooped back to London with mixed feelings of shame and relief.’
Despite Chamberlain’s claims of ‘peace in our time’, all he had actually done was buy time, at the expense of the Czechs, for Britain to prepare for war. The race to break the Enigma cyphers now had added urgency, but despite his undoubted brilliance Dilly Knox was having no success. In search of an answer, Denniston invited his opposite number in the French Deuxième Bureau, Colonel Gustave Bertrand, to London. The meeting was so secret that it was held away from Broadway Buildings with Bertrand referred to, even in correspondence between Denniston and Sinclair, as ‘Mr X’.
The British had exchanged information on Russian cyphers with the Deuxième Bureau’s codebreaking operation since 1933. But it was not until late 1938 that the two sides began to discuss the Enigma machine in any detail. Given that the exchange on Russian material had been somewhat one-sided, with the British providing far more than they received in return, the French had a surprisingly large amount of material on the Enigma machine. Denniston wrote to Sinclair suggesting that the dialogue was worth continuing. The French had clearly not got far themselves but had produced some 100 documents, some of which were of more value than others. They included ‘photographs of documents relating to the use of the Enigma machine which did increase our knowledge of the machine and have greatly aided our researches’, Denniston said. Bertrand made clear that some of the French material had been obtained by secret agents. In fact, it was largely from one Deuxième Bureau agent codenamed Asche.
Hans Thilo Schmidt worked in the German War Ministry’s cypher centre and, in exchange for money and sex, had provided the French with comprehensive details of the Wehrmacht Enigma systems. Schmidt was a ‘walk-in’, calling at the French embassy in Berlin in 1931 and offering to sell them documents on the use of Enigma in return for 10,000 marks. The critical handover came at a meeting between Asche and Bertrand at a hotel at Vervier, on the French-German border, in late 1932, when Asche produced two operators’ manuals, one of which had a message which had been encyphered using a real Enigma machine, and a schedule of daily Army keys for September and October 1932. They were photographed by the French allowing Asche to return the documents to the safe in the German War Ministry from which he had taken them before their absence could be spotted. Over the next six years, Asche produced numerous documents which were offered to the British and – until the November 1938 meeting with ‘Mr X’ – turned down, but which were passed on to the Poles.
Following the meeting with ‘Mr X’, Denniston asked Sinclair’s permission to continue the liaison with the French, explaining that
our main reason for seeking this liaison in the first place was the desire to leave no stone unturned which might lead to a solution of the Enigma Machine as used by various German services. This is of vital importance for us and the French have furnished us with documents which have assisted us but we are still doubtful if success can be obtained without further documents. During the coming meetings, we hope to show Mr X the lines on which we are working and make clear to him what other evidence we need in the hope that his agents may produce it.
The liaison with the French brought GC&CS a number of interesting documents, Cooper recalled. Since they arrived via the MI6 station in Paris in the same red jackets the British secret service used for all its reports, the French contributions were nicknamed ‘Scarlet Pimpernels’. They included documents on how to use the machine as well as photographs showing the Stecker system and how it worked, Cooper recalled. They also suggested that the French were not working alone.
They had not disclosed that they had other signals intelligence partners. But a Scarlet Pimpernel on the German Air Force Safety Service traffic had obviously been produced from material intercepted not in France but on the far side of the Reich. It gave data on stations in eastern Germany that were inaudible from Cheadle, but was weak on stations in the north-west that we knew well. Eventually, the French disclosed that they had a liaison with the Poles, and three-sided Anglo-Franco-Polish discussions began on the Enigma problem.
Denniston, Knox and Foss attended a meeting in Paris in early January 1939 with the French and representatives of the Bureau Szyfrow, Polish codebreaking organisation. The British codebreakers had high hopes that the meeting with the Polish codebreakers would help them to find a way to break Enigma. But it was to be a major disappointment. All three sides appear to have been too cautious to give anything of value away with Denniston describing the conference as having been held in ‘an atmosphere of secrecy and mystery’. The French codebreakers explained their own method of breaking Enigma, which was even less refined than the basic system used by Foss in 1927. Knox described his improved version of Foss’s system, which used a process known as ‘rodding’. The Poles were under orders to disclose nothing substantive and explained only how lazy operators set the machines in ways that produced pronounceable settings, such as swear words or the names of their girlfriends. This was something the British had already worked out and it was a great disappointment that they had nothing more to add, Foss recalled. ‘Knox kept muttering to Denniston, “But this is what Tiltman did,” while Denniston hushed him and told him to listen politely. Knox went and looked out of the window.’
Knox was dismissive of the claims made by both the French and the Poles, in the latter case wrongly but largely because the officer explaining them was clearly not a codebreaker himself and did not speak with any authority on the subject. Knox’s assessment of the Polish work was damning: ‘Practical knowledge of QWERTZU Enigma nil. Had succeeded in identifying indicators on precisely the methods always used here, but not till recently with success. He [the Polish officer] was enormously pleased with his success and declaimed a pamphlet, which contained nothing new to us.’
The main problem for Knox was what he called ‘the QWERTZU’, by which he meant the way in which the letters on the keyboard of the Wehrmacht Enigma machines were wired to the letters on the wheels inside the machine, and he left the meeting in Paris none the wiser. One good thing did however come out of the January 1939 meeting. It became clear that the Poles were using mathematicians to try to break Enigma and, when they returned to the UK, Denniston recruited two mathematicians to assist Knox. One was Alan Turing, a 27-year-old fellow of King’s College, Cambridge, who began working part-time, coming in on occasional days with the intention of joining full time when the war began. The other was Peter Twinn, a 23-year-old mathematician from Brasenose College, Oxford, who started work immediately.
‘When I joined GC&CS in early February 1939 and went to join Dilly Knox to work on the German services’ Enigma traffic, the outlook was not encouraging,’ Twinn recalled. Knox and the other leading GC&CS codebreakers were largely classicists or linguists, he said.
They regarded mathematicians as very strange beasts indeed and required a little persuasion before they believed they could do anything practical or helpful at all. The people working on Enigma were the celebrated Dilly Knox and a chap called Tony Kendrick, quite a character, who was once head boy [Captain of the School] at Eton. There was a slightly bizarre interview from Dilly who was a bit of a character to put it mildly. He didn’t believe in wasting too much time in training his assistant; he gave me a five-minute talk and left me to get on with it, which was actually rather good for me. Before I arrived Dilly was a lone hand, he always was, assisted by one secretary/assistant and enjoying a total lack of other facilities – though it is by no means clear that he would have used any. He was notorious for being very secretive about his ideas and I am not sure whether he had any hopes of ultimate success.
Dilly Knox was an exceptional man whose brilliance has only rarely been acknowledged. With the possible exception of John Tiltman, Knox was the only codebreaker of this era who proved as adept at breaking the old-fashioned codebooks of the First World War as the machine cyphers of Second World War. The son of a bishop, and the brother of the Roman Catholic theologian Ronnie Knox, he was fifty-five at the start of the war and so wildly eccentric as to put his fellow codebreakers in the shade. A fellow of King’s College, Cambridge, he walked with a limp, the result of a motorcycle accident, and wore horn-rimmed glasses without which he could see nothing. Knox was so absent-minded that he forgot to invite two of his three brothers to his own wedding. He believed so strongly in the relaxing powers of a bath to give him inspiration that during the First World War he had a bath installed in a room in the Admiralty. A fellow codebreaker recalled how, early in the war, the fellow lodgers in Knox’s billet became so concerned at the length of time he was spending in the bathroom that they felt compelled to break in. ‘They found him standing by the bath, a faint smile on his face, his gaze fixed on abstractions, both taps full on and the plug out. What was passing in his mind could possibly have solved a problem that was to win the war.’
Knox was in fact very close to breaking Enigma and there was just one major thing that was holding him up, Twinn recalled.
What we did not know was the order in which the letters of the keyboard were connected to the twenty-six input discs of the entry plate. Dilly, who had a taste for inventing fanciful jargon, called this the QWERTZU. We had no idea what the order was. We had tried QWERTZU, that didn’t work. There are twenty-six letters in the alphabet. Our ordinary alphabet has them in a certain order, but the Germans weren’t idiots. When they had the perfect opportunity to introduce a safe-guard to their machine by jumbling it up that would be the sensible thing to do. After all, there were millions of different ways of doing it.
The introduction of mathematicians to help Knox in his investigations of the Enigma problem was fortunately not the only good thing to come out of that first meeting with the Poles in Paris in January 1939. Knox might not have been initially impressed with the Poles, but they were certainly impressed with him and specifically asked that he be present at a second meeting between the Polish, British and French codebreakers, to be held at the Bureau Szyfrow, the Polish cypher bureau, in the Pyry Forest just outside Warsaw, in July 1939. It was only then that the Poles revealed the full extent of the progress they had made in reconstructing the Wehrmacht’s steckered Enigma machine.
The Bureau Szyfrow had broken a number of German codes during the early 1920s but the introduction of Enigma had left them unable to read the Wehrmacht’s messages. Their response was to recruit mathematics students and put them through a codebreaking course. Only three passed. Their names were Jerzy Różycki, Henryk Zygalski and Marian Rejewski. All three were recruited but worked initially on a part-time basis and it was only in September 1932 that Rejewski, the best of the three, was given the steckered Enigma machine and asked to solve it. By the end of that year, assisted by Enigma key lists obtained by the French from Asche, he had reconstructed the wiring mathematically, using permutation theory. By the beginning of 1938, assisted by the fact that the Germans were not changing the settings frequently, Rejewski and his colleagues were able to solve 75 per cent of the Poles’ intercepts of German Army Enigma messages. ‘We were decyphering every day and often at a record speed,’ he recalled.
In the autumn of that year, they began using electro-mechanical machinery known as Bomby – literally ‘bombs’, a name that derived from the ticking noise they made. The Bomby were used to identify ‘females’, repetitive letters in the Enigma keys, to break the messages. But the introduction, in December, of two additional wheels, allowing further different permutations of wheel order, brought the Polish successes to a halt. Rejewski succeeded in reconstructing the wiring of the two new wheels but the Poles no longer had enough Bomby to run through the much greater number of possibilities the new wheels had created. They needed help and believed the British could provide it, said Colonel Stefan Mayer, the officer in charge of the Bureau Szyfrow. ‘As the danger of war became tangibly near we decided to share our achievements regarding Enigma, even not yet complete, with the French and British sides, in the hope that working in three groups would facilitate and accelerate the final conquest of Enigma.’
The Poles explained how they used the Bomby and the Netzverfahren or ‘grid system’ invented by Zygalski. These were lettered sheets of paper with holes punched in them to help to break the keys and wheel orders by identifying the ‘females’. But the introduction of the fourth and fifth wheels had meant they had to use far more Bomby and sheets than they could possibly produce. Knox was furious to discover that the Poles had got there first, sitting in ‘stony silence’ as they described their progress and produced a clone of the Enigma machine, reconstructed using the knowledge they had built up over the previous six years. But his good humour soon returned after they told him that the keys were wired up to the encypherment mechanism in alphabetical order, A to A, B to B, etc. Although one female codebreaker had suggested this as a possibility, it had never been seriously considered, Twinn recalled. ‘It was such an obvious thing to do, really a silly thing to do, that nobody, not Dilly Knox or Tony Kendrick or Alan Turing, ever thought it worthwhile trying,’ he recalled. ‘I know in retrospect it looks daft. I can only say that’s how it struck all of us and none of the others were idiots.’
A few weeks later the Poles gave both the French and British codebreakers clones of the steckered Enigma. Bertrand, who had been given both machines and asked to pass one on to the British, later described taking the British copy to London on the Golden Arrow express train on 16 August 1939. He stepped down from the train at Victoria station to find the deputy head of MI6 Colonel Stewart Menzies standing on the platform, swathed in smoke and wearing a dinner jacket on which was pinned the rosette of the Legion d’Honneur. Bertrand handed the machine over to Menzies with the words, ‘Accueil Triomphal’ – ‘a triumphant welcome’.
As well as setting up the meetings with the French and the Poles, which would ultimately give the British the additional information they needed to break Enigma, Denniston began building up the organisation for war, touring the universities to search out academics, particularly mathematicians, linguists and classicists, with potential to become the new codebreakers his organisation would desperately need to first break the German cyphers and then keep on top of them. Sinclair got authorisation from the Treasury for the recruitment of ‘fifty-six senior men or women, with the right background and knowledge’ as well as thirty young female language graduates. Josh Cooper recalled:
It was often said, in the old GC&CS, that if we had another war we should have to mobilise the dons again. Denniston now went on a round of visits to the universities in order to sound out his former colleagues from the 1914–18 war, to find whether they would be prepared to rejoin in an emergency, and whether they could introduce him to other university teachers who might be useful and would be prepared to come. He dined at several High Tables in Oxford and Cambridge and came home with promises from a number of dons.
Denniston, who was by now fifty-seven, recalled that
it was naturally at that time impossible to give details of the work, nor was it always advisable to insist too much in these circles on the imminence of war. At certain universities, however, there were men now in senior positions who had worked in our ranks during 1914–18. These men knew the type required. Thus it fell out that our most successful recruiting occurred from these universities. During 1937 and 1938 we were able to arrange a series of courses to which we invited our recruits to give them a dim idea of what would be required of them.
The ‘territorial training course’ lasted about a fortnight; the first day was taken up with security indoctrination, after which the trainees visited a number of sections spending two or three days in each, with programmes arranged to suit the interests and qualifications of individuals. At the end of the course they were asked to say whether they would undertake to come to Bletchley on receipt of a telegram, and to say which section they would prefer to work with. Their pay was fixed at £600 a year with their colleges making up the balance of their normal salaries. The young female language graduates were not so fortunate, receiving just £3 a week.
Denniston is in many ways a tragic figure, never given the credit he deserved for his astute decision to work with the French, which led to the cooperation with the Poles, and to bring in mathematicians, a proposition that was never going to be welcomed by many of his more experienced staff. He would later be unceremoniously pushed aside and when he died in 1961 there were no obituaries pointing out the good work he had done for his country. But the work he put into recruiting academics, and particularly mathematicians, and preparing them to be called up on the outbreak of war showed a large degree of prescience and, as Cooper recalled, laid the foundations for the breaking of the Enigma cyphers that was to make such a major contribution to the Allied war effort.
It would I think be hard to exaggerate the importance for the future development of GC&CS. Not only had Denniston brought in scholars of the ‘humanities’, of the type of many of his own permanent staff, but he had also invited mathematicians of a somewhat different type who were specially attracted by the Enigma problem. I have heard some cynics on the permanent staff scoffing at this course; they did not realise that Denniston, for all his diminutive stature, was a bigger man than they.
Those recruited included Gordon Welchman, a 33-year-old mathematics lecturer and fellow of Sidney Sussex College, Cambridge, who would bring in a number of his students. Other more distinguished academics recruited to work at Bletchley included Professor Leonard Forster, a distinguished scholar of German and Renaissance Studies from Selwyn College, Cambridge; Norman Brooke Jopson, Professor of Comparative Philology at Cambridge, who was said to be ‘able to converse in most of the living languages of Europe’; Hugh Last, Professor of Ancient History at Brasenose College, Oxford; Tom Boase, Director of the Courtauld Institute and Professor of History of Art at the University of London; W. H. Bruford, Professor of German at Edinburgh, who had also served in Room 40; Gilbert Waterhouse, Professor of German, Queen’s University, Belfast; A. H. ‘Archie’ Campbell, Barber Professor of Jurisprudence at Birmingham; and J. R. R. Tolkien, Professor of Anglo-Saxon at Oxford University, who – sadly perhaps for codebreaking but not for the world of literature – eventually elected to remain at Oxford and write Lord of the Rings rather than join his fellow academics at Bletchley.
Patrick Wilkinson was one of those swept up by Denniston in his tour of the universities.
One day in the summer of 1938, after the Nazis had taken over Austria, I was sitting in my rooms at King’s when there was a knock on the door. In came F. E. Adcock, accompanied by a small, birdlike man with bright blue eyes whom he introduced as Commander Denniston. He asked whether, in the event of war, I would be willing to do confidential work for the Foreign Office. It sounded interesting, and I said I would. I was thereupon
