The Secret Life of Bletchley Park (6 page)

‘Of course the countryside around Bletchley was totally different from the countryside in the Highlands. It was a contrast. And I just loved it.’

These young recruits, as we have seen, were drawn from all across the country; many had left home for the very first time. The curious thing about the house at Bletchley Park, and the chalky lands around, was that they offered a calming backdrop to the deathly serious task in hand.

‘I was very interested in natural history,’ recalls Hut 6 code-breaker Oliver Lawn of some of the recreational pursuits that quickly took root at Bletchley. ‘And there was bird watching, and butterfly collecting.’ Of the brickworks immediately outside the town, says Mr Lawn, they ‘gave a scent, a smell, to the place. With brickworks, you take the clay out and make the bricks and it leaves great holes in the ground. Some of those holes filled with water, naturally. Some of them didn’t. The dry ones we used for shooting practice in the Home Guard. And the wet ones we used as swimming pools.’

And as the war went on, this oddly proportioned house was also to play a central role in some of the livelier recreational activities – nude outdoor bathing aside – enjoyed by the codebreakers.

From the day war was declared, the whole of Britain was, in a sense, mobilised. It was not merely the men waiting for their call-up papers. Everyone was set to do precisely as they were instructed by government officials, from giving homes to evacuee schoolchildren to taking jobs in factories. This sense of a total unity of purpose stretching across millions of people might seem a little difficult to imagine. What makes it easier is to bear in mind the very real, and acute, fear of invasion.

Austria, Czechoslovakia and now Poland had fallen to the Germans’ unprecedentedly swift and shockingly ruthless military machine. The young people of Britain found it all too easy to envisage those same ineluctable forces crossing the 22-mile distance across the Channel. For many, the very idea was literally the stuff of nightmares.

It was quite simple, explains Ruth Bourne, who was to become a Wren at Bletchley and elsewhere during the war. ‘More than anything else in the world, you didn’t want the Germans to win. Particularly me with my Jewish antecedents – I would not have wished anyone remotely connected with the Nazi situation to win.’

And in those first few weeks – amid the darkly ominous quiet that
took hold in Britain during the so-called Phoney War – the directorate at Bletchley Park knew that one of the most urgent priorities was to secure a break into the German navy’s Enigma messages. The prospect was a daunting one; that of cracking an enemy code system that was universally considered unbreakable.

In times of conflict, an island nation becomes uniquely vulnerable; if the enemy gains mastery over the seas, it will swiftly find ways to cut supplies of food and equipment to that island’s shores. And it was immediately clear that the German navy, with its U-boats, would aim to strangle Britain’s lifelines. It was for that reason that Bletchley Park’s director, Alistair Denniston, had taken the precaution of surrounding himself with so many of the cryptography experts with whom he had worked since the First World War.

Commander Denniston was known by some as ‘the little man’. A literal (and unkind) nickname referring to his short stature, it also obscured his many talents. He was trilingual; unusually, as a young man, he didn’t go to a British university, attending instead the Sorbonne and Bonn University. Denniston had also been something of an athlete in his youth: he played hockey in the 1908 Olympics for the Scottish team. Judging by the many memos that he sent in his time at Bletchley Park, and which have now surfaced in the archives, he was also a man of uncommon patience, especially when dealing with volcanic, quirky or short-tempered colleagues.

Perhaps in some ways Denniston was a little too diplomatic. According to his son Robin, the establishment that Denniston founded was brilliant, but he himself ‘was not … a man who found leadership easy. He lacked self-confidence. He was a highly intelligent self-made Scot who found it difficult to play a commanding role among the bureaucrats and politicians with whom he had to deal.’
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Women’s Auxiliary Air Force (WAAF) veteran Aileen Clayton said that Denniston ‘seemed more like a professor than a naval officer … I was immediately impressed by his kindness.’
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But there were those who saw how Denniston’s quality of kindness could be misinterpreted. ‘He was diffident and nervous,’
recalled Josh Cooper. ‘A small fish in a big pond that contained many predators.’

Denniston had been an expert on cryptography since the start of the First World War, when, as a young man, he had been summoned to the Admiralty, the chiefs of which had been eager to use his German expertise. In 1914, the Admiralty realised the tactical value of decoding and translating German naval signals, before distributing them throughout the British navy to give the forces a chance of being a step ahead.

During the First World War, the cryptographers had gathered in the department within the rambling Admiralty building known as Room 40. As a naval concern, Room 40 was in a perpetual state of rivalry with its army equivalent. Between 1914 and 1918, Denniston and his Room 40 colleagues acquired skills that went far beyond languages. And the stupendous feats of logic which they deployed to break into coded signals were noted by a fascinated young Winston Churchill, then First Lord of the Admiralty.

A naval operation it might have been, but Room 40 also had an atmosphere of academic informality. This was deepened with the arrival, in 1916, of the ferociously intelligent – and in some ways, simply ferocious – King’s College scholar called Alfred Dillwyn ‘Dilly’ Knox.

Knox was a classicist, but of an extremely unusual calibre: he was an expert on ancient papyri. This, ironically, provided him with the perfect flair and skill for codework. It would serve him especially well when squaring up to the challenge of Enigma.

Intriguingly, the First World War demands of Room 40 had dragged this irritable scholar away from deciphering one particularly beautiful and breathtakingly valuable papyrus found in southern Egypt: the 2,000-year-old
Mimiambi
of Herodas. Consisting of satiric dialogues only previously known by virtue of being mentioned in other Greek works, the discovery was wildly exciting to the academic world, much as if Aristotle’s Second Book of Poetics had been found.

Over the space of many years, Knox had travelled between Cambridge and the British Museum in Bloomsbury, there to study the intensely complicated strips of papyrus. The nature of Herodas’s dialogues was earthy, involving delinquents, brothels, slaves, sex-shops, flagellation and other such salty topics. But complications arose in deciphering such matters as where the speech breaks came, and indeed what was speech and what was not, and also in identifying errors of copying, since the papyrus may have been inscribed as a copy by an insufficiently attentive servant.

Then there was the question of how the crumbling text should be reassembled – how to ensure that the order was correct and that the pieces of the jigsaw were not out of place. This was a matter not merely of great classical learning or ability with language, but something of a cryptographical problem too. So when Knox was pulled into Room 40, the match seemed appropriate.

As soon as he arrived at work at the Admiralty in 1916, Knox bagged a room at the end of a long, untidy, undusted corridor; the room, arrestingly, also had a bath within it. This suited him extremely well; Knox was inordinately fond of hot baths.

And his department had an enormous early triumph: the decrypting of the so-called ‘Zimmerman Telegram’ – a message from the German foreign minister to the German ambassador in Mexico, urging that Mexico be encouraged into an alliance against the United States. It was this intelligence that brought America decisively into the First World War.

There was love (and laughter) in those dusty Room 40 corridors too; Alistair Denniston met his wife-to-be in the department. ‘The camaraderie of the members of Room 40,’ wrote Denniston’s son Robin, ‘all of whose names are inscribed on a silver salver which was given to Denniston and his bride on the occasion of their wedding in 1917, was borne out at the end of the war by … a pantomime, sung by all present. It was written by Frank Birch, himself one of the original cryptographers who left the secret service for the stage and for King’s College.’
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In the interwar period, the Government Code and Cypher School (as Room 40, reduced to a small number of codebreakers, was now known) had moved to Broadway Buildings and devoted itself largely to dealing with Soviet codes. Dilly Knox was especially adept in this area. Bolshevism, together with Stalin’s colossal ambition, was understood to be the most pervasive threat to the national interests. With Hitler’s seizure of power in Germany in 1933, however, those geopolitical tectonic plates shifted very rapidly.

The German navy had been using Enigma since 1926. The machine itself – the basic model of rotating letter wheels with electric contact studs, keyboard and lampboard with illuminated letters, all looking a little like a typewriter – was adapted by German electrical engineer Arthur Scherbius from an earlier, simpler design.

Enigma had been on the market since 1923, when it was used by a few commercial banks to make sure their communications were kept secret. Too few commercial banks, though: the machine was a commercial failure. Curiously, in 1926 the British government purchased one model after the machine was demonstrated at the Foreign Office. The War Office, felt, however, that it would be too ungainly for use in the field.

Once the German navy acquired the system, Enigma was completely taken off the open market, both military and commercial; the Germans then set about making a series of modifications that would make the machine’s security very much tighter. Soon afterwards, the system was adopted by the German air force, and then by the army. The British War Office had been perfectly wrong about it. The machine was brilliantly portable; thousands were manufactured.

The principle of Enigma was that the machines both enciphered messages and, at the other end, deciphered them. The operator would type a letter on the normal-looking keyboard; a couple of seconds later, via an electric current sent through the rotating code-letter wheels, another letter on the adjacent lampboard would
be illuminated. This substitute letter would be noted. And so on through all the letters of a message. The enciphered version would then be radioed in Morse to its intended recipient.

The recipient, with his Enigma machine set up in exactly the same way, would tap these encoded letters in, one by one – and one by one, the real letters would be illuminated on the lampboard.

‘Although it would have been possible for one cipher clerk to carry out all the tasks of the enciphering procedure himself,’ noted codebreaker Alan Stripp, ‘this would have been a lengthy and confusing process; normally it called for a team of two.’ Even with two, it was a time-consuming business. On top of this, the machine settings would be changed every twenty-four hours.

In 1927, GC&CS took the wise precaution of studying their basic, wholly unmodified Enigma machine. Hugh Foss – eventually to become a Bletchley leading light, brilliant at Japanese decrypts – was the man assigned to the job.

John Herivel later noted, in a tone of obvious admiration, the intricate innards of this aesthetically intriguing machine: ‘the function of the [letter] wheels with their studs, pins, rings and serrated flanges, how they could be taken in and out of the scrambler, the function of the left-hand reflector drum’ and ‘the wonderfully ingenious way each of the three wheels was forced into the nearest of 26 equally spaced “allowable” positions where they were firmly held, yet not so firmly that they could not be turned by finger pressure on the flanges to any one of the 25 other allowable positions’.
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And so this neat machine of bakelite and brass was an irresistibly beguiling prospect for any mathematician or logician. Even if the machine settings were being changed daily, there surely had to be some means by which the device could be defeated?

But there was an extra difficulty. The new German version had what was known as a stecker-board, or plug board, which made the machine’s wiring vastly more complex, and allowed for literally millions more potential encoding combinations. ‘The Germans regarded the Enigma as a perfectly secure machine,’ noted Stuart
Milner-Barry, who was at Bletchley in the early days of Hut 6. ‘Proof against cryptanalysts however talented and ingenious they may be.’

Right from the start, though, Hugh Foss wasn’t so sure about that. He wrote a paper saying that if enough could be gleaned about Enigma’s internal wiring, then the machine just might be broken with the use of cribs – basically using guessed words or phrases to give a starting point into all the other letters. One crucial key to the machine was that any letter – say, ‘W’ – could never be encrypted as itself. In other words, no matter how often one typed in ‘W’, the letter would never be encrypted as ‘W’. But this didn’t make the task of breaking the machine much easier to contemplate. There were still millions upon millions of potential combinations.

By 1936, when it was increasingly obvious within Whitehall that Hitler’s aggression would not be contained, GC&CS was applying renewed vigour to the Enigma problem. And in 1937, at the time of the Spanish Civil War, Dilly Knox devised a way into the earlier, unmodified version of the machine that was being used by Italy. He did this partly by means of ‘rodding’; Knox’s ‘rods’ were, in the most basic terms, a painstakingly calculated slide-rule style representation of the wiring and rotor position of the machine upon which cipher-text letters could be moved and rearranged.

And the British were not alone in these efforts. There was also invaluable aid from another source, for an early, slightly simpler German military version of the Enigma machine had been cracked as far back as 1932 by several gifted mathematicians in Poland.