The Secret Lives of Codebreakers

by Sinclair McKay

  In the deceptive quiet of those early weeks and months of the Phoney War, there was still time for theorizing and experimentation. “Some days it was actually very slack,” says John Herivel of his workload at that time. “You wouldn’t get that many intercepts in at all.” But as the season grew darker, even with all the clues and the help given by the Poles, the codebreakers knew they were facing an increasingly fearsome proposition.

  It was not just the mentally exhausting prospect of facing, day after day, these groups of random-looking letters, trying to think from every conceivable angle of some logical formula that would bring order to the chaos and make the letters resolve into language. It was also the knowledge that they simply had to succeed.

  The Italians provided a little succor. It was discovered that they were still using the earlier commercial version of the Enigma system, which although ingeniously complex, was known to be breakable. Dilly, with his rods and his fillies, was kept furiously busy in the Cottage, formulating means by which the Italian codes could be cracked by hand. At about the same time—the first Christmas at Bletchley Park, the ducks flapping in the freezing waters of the lake—Knox was also looking over Turing’s plans for new “bombe” machines—which were to prove revolutionary in their potential.

  But another obstacle for Bletchley was the fact that the different arms of the German military used subtly different versions of the Enigma system. The army Enigma machine was already fearsomely complex; the naval Enigma, as the cryptographers knew, was quite a different proposition—more complex, with extra code-wheels and more disciplined settings, using strict tables. Denniston doubted it could ever be beaten. For some of the new recruits making their way in blithe ignorance to Bletchley Park in the early months of the war, this would be the overriding priority.

  6 1939–40: The Enigma Initiation

  From the start, one of the disorientating elements about Bletchley for a new recruit was the ambiguity of its status. It seemed to be neither a military nor a civilian operation, but—especially in its earliest days—a curious blend of the two.

  In other words, this was not an environment of uniform, parade grounds, and drill. And as work gathered pace, and the responsibility for breaking codes was divided between services—army, air force, naval—and sectioned off into separate huts, the place remained curiously self-governing and self-disciplining. If you worked in Hut 8 on the naval Enigma, for instance, you answered to the head of Hut 8 and seemingly no one else.

  This vagueness of structure, combined with the nature of the personnel that Bletchley Park acquired, was the cause of some initial discomfort and bewilderment in Whitehall. As veteran and historian Harry Hinsley wrote of the organization of the Park:

  [It] remained a loose collection of groups rather than forming a single, tidy organization.… Professors, lecturers, and undergraduates; chessmasters and experts from the principal museums; barristers and antiquarian booksellers, some of the in uniform and some civilians on the books of the Foreign Office or the Service ministries—such for the most part were the individuals who inaugurated and manned the various cells which sprang up within or alongside the original sections.

  They contributed by their variety and individuality to the lack of uniformity. There is also no doubt that they thrived on it, as they did on the absence at GC&CS of any emphasis on rank or insistence on hierarchy.1

  Lord Dacre, then Hugh Trevor-Roper, was attached to Intelligence at the time and quite often passed through the Park. He was reported as saying that the early years of Bletchley were marked with “friendly informality verging on apparent anarchy.”

  Perhaps the only parallel with the call-up to the military was that the summons for Bletchley was not questioned by anyone who received it. However, unlike the weeks of careful training that one received for military service—the weapons handling, the exercises—Bletchley seems to have been something of a plunge pool. For the early codebreakers and linguists alike, there was an element of being parachuted straight in to their new lives with little in the way of instruction. There are those who recall short, intensive courses for beginners being held in a nearby school; according to others, there wasn’t even that.

  “It was all pretty quick,” says John Herivel. “I think especially for those of us who arrived in the early days. I was shown the Enigma, and packed off to see Alan Turing and Tony Kendrick. They were, in a sense, my teachers.”

  Oliver Lawn, who arrived a little later, found himself feeling quite gung ho about the nature of the challenges that lay ahead. He recalls: “These were basically mathematical problems and I had been trained as a mathematician, to spend my life doing these problems. This was just another form of problem.”

  According to Mavis Batey the whole thing was more random than that. She recalls with some amusement the startlingly hands-off approach when she first joined Dilly Knox in the Cottage: “We were all thrown in at the deep end. No one knew how the blessed thing worked. When I first arrived, I was told, ‘We are breaking machines, have you got a pencil?’

  “And that was it. You got no explanation. I never saw an Enigma machine. Dilly Knox was able to reduce it—I won’t say to a game, but a sort of linguistic puzzle. It was rather like driving a car while having no idea what goes on under the bonnet.”

  Mathematician Keith Batey is amused to this day about his initiation to the new, esoteric world of Enigma: “I arrived with two other chaps from the maths tripos. We were greeted at the Registry and were immediately given a quick lecture on the German wireless network. And I didn’t pay much attention because I was focusing on these highly nubile young ladies who were wandering about the Park.

  “Anyway, after twenty minutes of this lecture, which told us absolutely nothing,” continues Mr. Batey, “we were handed over to Hugh Alexander, who was the chess champion. He sat us down in front of what later turned out to be a steckered Enigma, and he talked about it. It didn’t have a battery, it didn’t work. And then we were just told to get on with it. That was the cryptographic training.”

  Bletchley Park seemed an organic kind of institution. Perhaps, given the early, experimental nature of the work—so many minds attacking the problem of the codes in so many ways—there was little point in trying to give it an over-rigid structure. Nevertheless, in contrast to strict naval and military hierarchy, the place from the start seemed curiously self-disciplined. “There were an awful lot of people who just used first names,” recalled one veteran, surprisingly given how socially formal the period was.

  Meanwhile, Alistair Denniston’s administrative difficulties were growing. There were problems involving accommodation for all the staff. An adjacent school—Elmers School—had to be requisitioned as more huts underwent construction.

  Looking at these old huts now, one cannot help wondering why the authorities did not base the codebreaking activity in rather more comfortable, better-built space. One possible answer is that at that stage, no one anticipated the war lasting long enough for permanent structures to be needed. After all, even up until the summer of 1939, there were many who believed that Chamberlain’s government would, of necessity, allow Hitler to get away with further acts of aggression throughout Europe. Perhaps another consideration was that it was vital that no unfriendly attention was drawn to the Park. Not only would extensive building work raise questions, but it would also be more easily visible from the air by enemy reconnaissance pilots.

  And so a series of huts were constructed and accorded separate functions, decided by the sorts of codes that were to be read. By the side of the house was Hut 4, which was to become the Naval Section hut. Hut 5 was to become the Military (and later, the Japanese) Section. Other huts, such as Hut 8, the home of the Naval Enigma operation, followed not too long afterward.

  Hut 3—which, together with Hut 6, seemed to form the hub of the operation—was nominated in part for army/air intercepts and Intelligence work; Hut 6 was where air force keys were to be read. Hut 1 eventually came to house the first experimen
tal Turing bombe deciphering machine. (And according to Mimi Gallilee, “Hut 2 was for beer, tea, and relaxation.”)

  From the very start, for the sake of security, the functions of each hut were kept as separate from one another as possible. Personnel were instructed that inter-hut discussions were forbidden. Absolute secrecy was a given. “You just assumed,” says Keith Batey drily, “that you’d be shot.” Recruits would be allocated to their hut and, during working hours, would be metaphorically hermetically sealed within. No one else, save the occasional messenger, would be allowed entry.

  Even though the word “hut” implies a cramped construction, these were long structures, with central passageways and rooms off either side. There were plain windows (shuttered at night for blackout purposes), floors of squeaky lino, basic desks and chairs. Green-shaded lights hung from the ceiling. A great many people worked side by side among plain filing cabinets; the rooms were suffocating in the summer sun, and draughty and cold in the depths of winter. As one cryptologist commented: “Nothing…seemed less likely to house great matters than the ramshackle wooden building (its atmosphere nauseating at night when the blackout imprisoned the fumes from leaky coke-burning stoves) to which I reported…”

  Heating was a perennial problem. Mittens were commonplace. Added to this was a faintly comical, Heath Robinson dimension: messages were passed between some huts by means of an extemporized wooden “tunnel” and propelled by means of a tray with wheels on the bottom, and a long broom handle.

  John Herivel recalled the unique atmosphere in the ill-ventilated and sporadically heated huts. There were the big tables, covered with maps. Then there were the spartan lights giving out yellowish light on the simple desks and the bare whitewashed walls. Mr. Herivel recalls that he was “provided with a blackboard set on a low table” so that he could write while seated. And before him was a desk piled with intercepted messages.

  The phrase “need to know” was constantly evoked. Even for the young messenger girl Mimi Gallilee, moving from hut to hut delivering the post and packages entry was sometimes forbidden. Even though her older sister worked in Hut 10 alongside Josh Cooper, Mrs. Gallilee recalls: “I never knew what my sister did in Hut 10. I never even asked her. She wouldn’t have told me anyway. She knew where I worked. Later, when I was promoted and moved into office work at the house, she never came to my department. I had to go to Hut 10 on a few occasions for my own department. I’d be asked to go over to Commander This or Squadron Leader That in Hut 10 and I’d see my sister sometimes.

  “On the few occasions when I had to go over to her hut to talk to someone—if it was in the room she was working, I can remember seeing pieces of paper—not slips of paper but sets of figures. And so my sister would have been working on figures or letters, I don’t know which.”

  As the work of the Park continued to expand, so too did the demands for space. The Secret Intelligence Service had now, briefly, evacuated to Bletchley. They were occupying the upper floors of the house, though thanks not only to issues of space but also to straightforward operational concerns, they did not stay long. Meanwhile, in the early days, the ground floor played host to GC&CS, with the numbers growing daily. The corridors of the house were full of trestle tables. The telephone exchange was in the ballroom. The Naval Section, for a while, had to find a temporary home in the library.

  For Dilly Knox, Alan Turing, and Gordon Welchman, sanctuary was found in the Cottage. By this time, Turing, then just turned twenty-eight, was already at work on the design of his revolutionary bombe machine.

  In these first few months, the irascible Dilly Knox was beginning to take stock of the people that he had gathered around him. In a handwritten letter to Denniston, he reported of his young underlings: “As you know, Joan H. is a great personal friend of my family and myself. But as a secretary, she is frankly a flop.” Knox then gave his bullet-pointed appraisals of the others:

  A few notes on senior staff:

  a) Kendrick is quite admirable. It is a pity I have put him in the [Elmers] school since, tho’ he has a lot to learn, he is the obvious second (or first?) in command.

  b) Welchman is doing well and is v keen. I hope to get him back here [from Elmers School] to learn about the machines.

  c) Twinn is still very keen and not afraid of work.

  Knox’s attitude toward the young Alan Turing was more ambivalent:

  He is very difficult to anchor down.

  He is very clever but quite irresponsible and throws out a mass of suggestions of all degrees of merit. I have just, but only just, enough authority and ability to keep him and his ideas in some sort of order and discipline. But he is very nice about it all.2

  For a little while, there was some tension between Dilly Knox and Gordon Welchman. Knox as the senior cryptographer felt that the Cottage was overcrowded. So Welchman was exiled to the nearby temporarily requisitioned Elmers School (as the memo cited on page 54 indicates, Knox was keen that the exile should be short). The idea was that, rather than codebreaking, Welchman would be trying to crack the slightly different problem of “traffic analysis.” This involved studying the origins of intercepted signals to work out where they came from, and thereby hopefully making deductions about military movements.

  Welchman wrongly inferred from his exile that Knox had taken a dislike to him; as a result, he seemed to suffer slightly from wounded pride. It also seems to be the case that Welchman wasn’t smitten by Knox himself. Years later, he wrote: “He was neither an organization man nor a technical man. He was, essentially, an idea-struck man… By and large Dilly seems to have disliked most of the men with whom he came into contact.”3

  Knox might well have smelled something to his distaste about the younger man; for very early on, Welchman was working on schemes to restructure and reorganize the entire codebreaking operation, in such a way that a great deal of power and authority would have slipped from Knox’s hands.

  Indeed, Welchman wasted no time at all during his exile. Mathematician John Herivel recalls one of the key innovations. Welchman was quick to form a strong working relationship with the most secret listening station—“an old fort” at Chatham, Kent, on the Thames estuary. It was through this establishment that, at that time, much of the German signaling traffic came.

  Once the signals were picked up, the officers at Chatham would have bundles of intercepted coded messages sent to Welchman. These bundles would be driven from the coast to Bletchley, through the middle of the night and at harum-scarum speeds, often in the most atrocious weather conditions, by special motorcycle couriers.

  The German rule was that no message should be more than 250 letters in length; if it was necessary to send a longer message, it should be split into multiple parts. This was designed to make life more difficult for codebreakers: the longer the message, the easier it might be for such a person to see patterns of letters forming among the apparent chaos.

  But each Enigma message had a preamble and some operators used different discriminants (that is, groups of characters indicating the code setup and reciphering key, and distinguishing the section of traffic) for the different parts. As Herivel noted, it was thus possible to work out any “given key.” “In this way,” he wrote, “all the different German keys coming from Chatham—and later from France—could be identified, and every day, traffic could be divided into different bundles for different keys.”

  The keys were then given different colors to separate them out in the most direct visual way. To start with, the colors used were yellow, green, red, and blue, respectively signifying the German Norway campaign, the army and air force codes, and separate air force training codes. The time and the frequency of each message would be noted down on vast sheets of paper, leading to an immediate strain on the Park’s supply of colored pencils. But the color keys were a stroke of organizational genius—a vivid signifier that allowed everyone to identify each key with ease. Indeed, Welchman recalled in his memoir that one element of recruitment to Bletchley Park involved
asking candidates “if they were color-blind.”

  In our world of ubiquitous touch-screen technology, such a system smells of pencil shavings and glue and bits of string. But it worked. The avalanche of thousands upon thousands of intercepts—the numbers of which would multiply dramatically as the Phoney War ended and the conflict intensified—had order imposed upon it. It could be deduced from which part of the German military they were being sent, and to which.

  It soon became necessary to develop subdivisions for the keys (such as SS messages, and messages to do with German railways); before long every color in the rainbow was deployed. When all available colors had been used, keys were named after marine life: birds, then elephants, and insects…

  There were many occasions when a message could not be broken in its entirety, because words were missing or incomplete. As a result, a comment would be added with the words “strong indications,” “fair indications,” or “slight indications” to convey the varying degrees of the decrypt’s reliability. But it was through the work of Chatham—and later other intercept stations such as Denmark Hill in south London—that Welchman began to understand about the different call-signs used by different operators, and what signs would be used for what sorts of messages.

  Dilly Knox was also using the period of the Phoney War to get himself and his team ready for the onslaught of work that was to come. The difference between Knox and Welchman was Knox’s apparent taste for pulchritude on his team, although now Mavis Batey laughs off—with a very faint edge of annoyance—any idea that she was recruited chiefly for reasons of glamour: “Dilly was very firm. He said he did not want any debutantes who had got there by Daddy’s knowing someone in the Foreign Office. Equally, he said, he didn’t want a yard of Wrens who all looked alike and you couldn’t tell one from the other.