The Secrets of Station X (3 page)

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.

T
he 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:

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

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.

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.

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.’