The Secrets of Station X

by Michael Smith

  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 a
nd 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.