The Secret Life of Bletchley Park

by Sinclair McKay

  Josh Cooper and Colonel Tiltman were not only heads of expanding sections, they were both distinguished cryptanalysts. I was far too wrapped up in my own work on Enigma to know about the breaking of other codes and ciphers under these two experts. I remember, however, being told by Josh Cooper that his work was an almost intolerable strain.

  Success so often depended on flashes of inspiration for which he would be searching day and night, with the clock always running against him.7

  Despite the strain that he felt personally, Josh Cooper was an object of admiration even to those from outside the Park. ‘He was one of the most unforgettable people I have ever met,’ recalled WAAF signals intelligence operative Aileen Clayton, who at that time was based at the Kingsdown Y-station. ‘A brilliant mathematician, and much younger than he appeared to be at first sight, he was the archetypal absent-minded academic – slightly deaf, incredibly unkempt in his dress, dark hair flopping over his face, hair which he constantly brushed back with a vaguely irritated gesture, often thereby dislodging his thick spectacles. Yet one was aware of an inner brilliance.’8

  Clayton went on to describe how, just as she entered his hut, Cooper was starting to go through some scraps of paper – not encrypted messages, but odds and ends from the pockets of a German bomber shot down over East Anglia. In the manner of Sherlock Holmes – and before the widening eyes of young Miss Clayton – he began to assemble, from old tickets and a cigarette packet, the pilot’s exact movements on the continent prior to his mission.

  It was not merely an intellectual exercise. The more information one could glean, the more the bomber’s interrogators could startle him with their apparent knowledge of his comings and goings – and in so doing, startle him into giving away further information.

  ‘Nowadays,’ recalled Aileen Clayton, ‘we are blasé about detective stories, seeing them so often on the television – but to me, then, it was quite fascinating to see how, from such little things, so much information could be gleaned.’

  So while the pressure was obviously intense, in another sense, the game was also afoot. And for others at Bletchley Park, this was precisely the reason why they seemed not to become quite so highly strung. For instance, Alan Turing’s biographer Andrew Hodges throws intriguing light on the way that many of the ‘boffins’ may have viewed this branch of war work:

  Nor was there any pretence at heroism in Bletchley circles. It was not simply that Intelligence traditionally represented the most gentlemanly war work; not simply that the unspoken agreement was that of doing one’s bit while making as little fuss as possible. For at the higher levels, the cryptanalytic work was intensely enjoyable.

  Being paid, or otherwise rewarded, seemed almost a curiosity. It was also something of a holiday even from professional mathematics, for the kind of work required was more on the line of ingenious application of elementary ideas, rather than pushing back the frontiers of scientific knowledge. It was like a solid diet of the hard puzzles in the New Statesman, with the difference that no one knew that solutions existed.9

  For the young codebreakers, working in hermetically sealed departments, under the strictest instructions not even to talk to one another about their work, there was another factor that rendered it sometimes a little abstract. Josh Cooper, in a rare moment of disclosure intended to raise morale, once praised a young codebreaker’s work by saying that it was ‘helping to save lives in the Atlantic’. But information was generally almost non-existent. ‘What you didn’t know was the effect that this was all having upon the war,’ says Oliver Lawn. ‘You see, we knew no more than the public news bulletins, which were obviously censored.’

  Very occasionally, there would be a shockingly vivid reminder of what was going on outside. ‘The only time I actually realised what we were doing was when I was shown a notebook,’ recalled Gwen Watkins. ‘It had just been captured and rushed to Bletchley from a captured plane, and of course we had no plastic envelopes or anything then, the poor thing was just given to me as it was. And I was horrified to see a huge bloodstain on it. The blood round the edges was drying, but the blood in the middle was still wet.

  ‘And I realised then that somewhere there was this German. This German air-crew bleeding, still bleeding while I was decoding. That did bring the war very close.’10

  But these moments were vastly outnumbered by the sense of simply getting on with it, working almost in a void – a feeling to which the nature of the shift system itself contributed. Veterans recall starting a shift, with perhaps a pile of intercepts waiting either to be cracked or to be translated. Segregated in different huts, and under strict instructions never to discuss their work outside the Park, when the shift came to an end and it was time either to go back to a billet in town, or even for a bicycle ride in the countryside, there was little else one could do but pass the baton to those coming in on the following shift. And try to forget about it all, as indeed they were instructed to do.

  ‘I don’t think it was particularly intense,’ says Keith Batey, drily. ‘Well, mathematicians tend to be phlegmatic.’

  The mathematicians stayed so. But as the war progressed, elements of friction and stress within the organisation of the Park itself would come to the fore and be felt by all. Before that, though, came Bletchley Park’s magnificent moment of technological breakthrough – the introduction of the bombe machines.

  10 1940:The Coming of the Bombes

  Secret service officer Frederick Winterbotham described the bombe as ‘like some Eastern goddess who was destined to become the oracle of Bletchley’.1 The machine’s origins were more prosaic, although inspiration had its place in their development.

  Alan Turing had, among other attributes, a tremendous gift for building things from scratch. When it came to electrical experiments, he was the master of what popular fiction authors always describe as ‘lash-ups’. Even in the years that followed the war, with all the technological progress that had been made, Turing’s devices tended to fulfil the stereotype of the mad scientist’s invention: a labyrinth of wires trailing everywhere, held together with sticking plaster. Prior to his premature death in 1954, his home in Manchester was filled with extraordinary and sometimes pungent chemical experiments.

  Turing had fixed upon the idea of a ‘Universal Turing Machine’ in the 1930s; the inspiration had been provided by a mathematical problem posed in Cambridge, concerning the provability of any given mathematical assertion. Turing had the idea of developing a machine that could carry out this task.

  When first trying to envisage the form of such a machine, Turing thought of typewriters, how they were built to carry out a certain sort of function. According to his biographer Andrew Hodges, he had in his head an idea of a super-typewriter: a machine that could identify symbols; that could write, but could also erase. A machine that could be configured in many ways to carry out many tasks, and yet would be automatic, requiring little or no intervention from a human operator. His argument was that any calculation that a human could perform, a machine could perform as well.

  The bombes were not Universal Turing Machines. Far from it. Nor were they an extension of the Polish ‘bomba’ machines, from which their name was taken. The British bombe was quite a different thing.

  In one sense, it was a philosophical response to the nature of Enigma. Despite the daunting number of combinations thrown up by Enigma, it none the less worked via a mechanical process. Thus, reasoned Turing, Enigma could also be thwarted mechanically. If Enigma, with its rotors, and wiring, and steckerboard, could encrypt, then surely an electric system involving circuits could decrypt.

  As many veterans have pointed out, this wasn’t an entirely mechanical affair. For a bombe to work, it would require the push-start of a crib; that is, a series of words or a phrase, guessed at by hand and offered to the machine – which would then run through all the different letters and combinations to see if the crib would unravel the encoded text. In other words, such a machine would still require the initial power of hum
an lateral thought. Nevertheless, in an era in which electronic telephone exchanges and television signals were brand new science, the notion of a machine that could take on the exhausting task of checking endless combinations at a speed beyond even an army of codebreakers was revolutionary.

  When the young mathematician Oliver Lawn was recruited to Bletchley Park by Gordon Welchman, he found himself being diverted into the business of creating a bombe that would be effective. Construction took place in Letchworth, where Lawn oversaw this delicate and confidential work. In a technological sense, it was almost like being present at the construction of the first nuclear device. Certainly the impact that Turing’s codebreaking machine would have on the course of the war was immeasurably as profound.

  ‘Turing was a theoretician, Welchman was the practical chap,’ Mr Lawn says. ‘And the two put together their brainpower and evolved this machine which was made in large quantities in Letchworth by the British Tabulating Machine Company, as it was then called. In my early months, the first machines were being made.

  ‘I and several others used to go over and stay in a hotel in Baldock near Letchworth and work with the engineers on the making of the machine. The engineers had their engineering skill, we had none of that, but we had the mathematical skill. And we worked with the engineers – the chief engineer was Harold Keen, known familiarly as “Doc” Keen because he used to carry what looked like a doctor’s bag in his hand. He was a very bright engineer.

  ‘Because the Germans had devised new ways of encrypting, we had to find new methods to break the codes,’ he adds. ‘Eventually we got on to using cribs, guessing bits of messages, and testing them on the bombe machines which Turing and Welchman together had conceived. Then when the design of the machine was more or less settled, ‘they got on with it and more were produced. We weren’t needed after.’

  The first bombe was called ‘Victory’. Given the months of painstaking work that had gone into its creation – and the acute sensitivity of the job that it was required to do – there was some debate on how the machine should be physically transported with maximum safety, and secrecy, from Letchworth to Bletchley.

  Some felt that such a vital device needed all the security that it could get, and that it would have to be taken with a full convoy of protection. However, if there was enemy undercover surveillance about, such a convoy would make obvious the strategic importance of both the machine and its destination. And that could not be allowed. So, perhaps surprisingly, Victory was transported in an open lorry, with no escort of any kind.

  The one-ton machine was installed in Hut 1 on 18 March 1940. It did not immediately prove to be the answer to Allied prayers; indeed, it achieved very little in terms of key-setting results. The essence of the machine was that, like a giant calculator, it cycled through every possible combination of the three Enigma code wheels. When the machine hit the menu provided to the bombe operator by the cryptographer it would hit a ‘stop’. There would be good ‘stops’ and bad ‘stops’, which would all have to be checked.

  There would be little unintentional outbreaks of assistance from the Germans, examples of idleness that provided invaluable clues. There were Enigma operators who ended each message with the proclamation: ‘Heil Hitler!’ and others who started each communication with a list of names for which it was intended. However, the first breaks into a new key were very difficult.

  Alan Turing’s friend – and briefly, fiancée – Joan Murray worked specifically on naval Enigma and made much use of Victory early in 1940. The messages that were decoded turned out not to be of much direct value, but they did allow intelligence to build good background information about the navy itself. The work was gruelling; Joan and Turing often had to go through each of the possible 336 wheel orders.

  Soon, however, a crucial breakthrough was made in the design of the bombe machines. This time the credit went to Gordon Welchman, as Andrew Hodges described in his biography of Alan Turing: ‘on studying the Turing bombe design, he saw that it failed to exploit Enigma weakness to the full … Welchman not only saw the possibility of improvement, but quickly solved the problem of how to incorporate the further implications into a mechanical process.’ It required only a piece of electrical circuitry – soon to be called ‘the diagonal board … the following of implications could still be achieved by the virtually instantaneous flow of electricity into a connected circuit’. Hodges continued:

  Welchman could hardly believe that he had solved the problem, but drew a rough wiring diagram and convinced himself that it would work. Hurrying to the Cottage, he showed it to Alan, who was also incredulous at first, but rapidly became equally excited about the possibilities it opened up. It was a spectacular improvement … With the addition of a diagonal board, the bombe would enjoy an almost uncanny elegance and power.2

  On 9 April 1940, the Germans landed in both Denmark and Norway with 15,000 troops, catching the British completely by surprise. Indeed, only four days beforehand, British ships had set sail in order to lay mines in Norwegian waters, prompting Neville Chamberlain to prematurely declare that ‘Hitler has missed the bus.’

  The following month saw the German invasion of Belgium, Holland, Luxembourg and then, with astonishing and appalling speed, France – a full-scale offensive every bit as brutal as that against Poland. The British Expeditionary Force was encircled and nudged back towards Dunkirk. Prime Minister Neville Chamberlain resigned, and the government collapsed beneath him.

  On 10 May Winston Churchill became Prime Minister, heading a National Government. Although the French had been under the impression that the British would leave a force behind, he immediately ordered the evacuation of British forces across the Channel. Then came the fall of Paris; and if one reads the many British Mass Observation diaries now, one is left in no doubt that the British were convinced that they were next.

  The country was in a state of agonised suspense. From Mass Observation to the diaries of society figures such as Harold Nicolson, there is a sense of an almost dreamlike mental state; London and the larger cities were undergoing nightly bombing raids. The Nazi war machine appeared utterly inexorable.

  But before the extraordinary and exceedingly fortunate retreat at Dunkirk, Bletchley made another vitally important breakthrough. In a further triumph for the Herivel Tip, it broke the ‘Red’ Enigma key. To have a way into the German air force messages was a glittering prize. ‘The Red became of vital importance immediately,’ commented one veteran of Hut 6, ‘and remained so all the way through the war and in all the main theatres of war except Africa … The Red was the great standby that kept Hut 6 going. I cannot remember any period when we were held up [in decoding] for more than a few days at a time.’

  From that point onwards, the Park was able to read, on a daily basis, every single Luftwaffe message – something in the region of one thousand a day. The messages also gave vital clues as to the movements of land troops. The latest setback was that the messages were also filled with technical jargon: abbreviations, equipment terms, out-of-date map references. In the short term, the intelligence yielded was of no use whatsoever to the thousands of British troops gathered on the French beaches at Dunkirk, awaiting the deliverance of the little ships. But in principle it was a fantastic breakthrough; and the difficulties would be overcome with time and experience.

  There was an important psychological point too, one that would have been relayed to Churchill; in the midst of all these decrypts, it was obvious that the main German concern at that moment was the successful conquest of France. There was no mention at that stage in May 1940 of plans to invade Britain. Not one of the thousands of decrypts had suggested that there was going to be an incursion from across the Channel.

  By June 1940, however, the decrypts were throwing up intelligence concerning the refit of the Luftwaffe, which strongly suggested that a bombing campaign against Britain was imminent. ‘Enigma gave general warning of the approach of the Battle of Britain,’ wrote codebreaker Sir Harry Hinsley. ‘The
fact that Enigma had now been producing intelligence for some months on the German Air Force’s organisation, order of battle and equipment was also of great strategic value.’3

  Indeed, thanks to Bletchley Park – the information was described as ‘heaven-sent’ and ‘apparently sure’ – Air Intelligence and the RAF gained a much more realistic idea of German bomber strength, and was given a vital boost of confidence; the enemy forces were not quite as multitudinous as had been first thought. On top of this, the cumulative effect of listening in to so many messages had the effect of bolstering Churchill’s determination. Thanks to the decrypts, he knew that he and the British had just a little extra time.

  In fact, on 16 July 1940, with the German subjugation of France consolidated, Hitler issued Directive no. 16, involving preparations for ‘a landing operation against England’. The plan was called ‘Operation Sea Lion’ – a phrase that, ominously, was picked up with increasing frequency thereafter by the decrypters – and an initial air offensive was to begin on 5 August.

  This then was the background to the Battle of Britain – that extraordinary moment when, as Bletchley veteran Captain Jerry Roberts now puts it, ‘one tiny blob to the north of the map of Europe’ stood its ground while all others around it fell. Even though Bletchley could not be of practical assistance to British planes as the battle was fought, the help it had provided beforehand was immeasurably valuable.

  And in the midst of the national anxiety, there was one other small, but vital fillip for the Chiefs of Staff: they had learned that the Germans could be outwitted. Their sheer physical force may have seemed unbeatable but to have advance notice of plans and manoeuvres made their threat, at last, surmountable in theory.

  Initially, the bombe machines were operated and serviced by specially picked RAF technicians, headed by a Sergeant Jones. After weeks of frustration during which Victory produced endless false stops, as Sergeant Jones wrote later, ‘it was realised that some radical change was still required … So the theorists, the cryptographers, the engineers, professors, doctors, got together and decided what was needed.’