The Debs of Bletchley Park and Other Stories (19 page)

Dilly was so absent-minded that he forgot to invite two of his three brothers to his own wedding in 1920. He had so many of his best ideas while relaxing in the bath that during the First World
War he had a bathtub installed in his office in the Admiralty. At one point, his fellow codebreakers became concerned and, thinking something must have happened to him, broke into his office, only
to find him sat in the bath with the plug pulled out and both taps full on while he stared at the wall deep in thought, trying to solve a coding puzzle.

Commander Denniston reopened the Cottage and put Dilly in charge of a research section looking into unbroken machine codes that Hut 6 didn’t have time to deal with. Manning the section
would be a problem. Although Dilly had liked and trusted Alan Turing, Peter Twinn and Tony Kendrick, he clearly had little patience with the new young men who were coming in with their own ideas of
how the work should be done. They all seemed to want to make their names, to prove themselves. Dilly was naturally a loner. He was certainly not prepared to work with anyone arrogant enough to
believe they could teach him how to do his job. So Denniston agreed to recruit a team of young women to help Dilly. They would swiftly become known as ‘Dilly’s Girls’.

The first recruits were the daughters of two members of Denniston’s golf club, Joyce Fox-Male and Claire Harding, who at twenty-seven was to be office manager. As well as
clerical support, Dilly needed someone to manage his codebreaking work and Denniston was keen it should be a mathematician. Margaret Rock was ideal. She was thirty-six, so just a bit
older than the other girls, and had studied at Bedford College, London, before becoming a statistician. She had precisely the sort of ordered mind that Dilly needed to complement his madcap ideas,
and arrived in the Cottage in April 1940.

Dilly had very clear ideas of what girls he needed in his research section. A mathematician was one of the most obvious requirements, and another was at least one German linguist, if not more.
He certainly didn’t want any debs whose daddies had persuaded a friend at the Foreign Office to find them a place at Bletchley. He wanted women with ability whatever their background.

Mavis Lever was already working for the Code and Cypher School when the Cottage was reopened but she was not based at Bletchley Park. Mavis was breaking commercial codes at the pre-war
headquarters in Broadway Buildings in London. She’d been born in May 1921 in Dulwich, south London; her father worked in the local postal sorting office and her mother was a seamstress. Mavis
attended Coloma Convent School in West Croydon where she studied German as one of her languages. As a child she and her parents traditionally took their holidays in Bournemouth but in the 1930s
Joseph Goebbels, Hitler’s propaganda chief, had created a programme of cheap holidays to Germany under the title of
Kraft durch Freude
(‘Strength through Joy’) and in
1936 at the age of fifteen Mavis persuaded her mother and father that this year they should go to the Rhineland.

‘We bought cheap tickets for a steamer trip along the River Rhine. We joined crowds of happy German workers with free tickets. They were to be indoctrinated into the
myths and legends of German heroes. Wagner’s blonde Rhine Maidens were with us constantly and the band struck up as we passed the Lorelei. I lapped it all up and when I got back decided to
opt for German literature in the sixth form.’

Mavis earned a place at University College London studying German Romanticism under Professor Leonard Willoughby, one of Dilly’s closest colleagues in Room 40 during the First World War.
Mavis was due to go to Tübingen University in Germany for a term in 1938 but, with war increasingly likely, she was switched to Zurich University instead.

‘I stayed there until war was imminent and by the time I got home the Siegfried Line between France and Germany was being manned so I just got back to UCL in time and found they were
evacuating to Aberystwyth. I wanted to do something better for the war effort than read poetry in Wales, so I said I’d train as a nurse, but I was told: “Oh, no you don’t. Not
with your German.”’

Mavis was interviewed at the Foreign Office and selected as an ideal candidate for a job in intelligence but her suitability for secret work was put briefly under the spotlight after two German
‘Jewish’ refugees she had sponsored at UCL, helping them to find work at a country house in Kent, were arrested as spies. Eventually she was cleared of anything but naivety and sent to
the MI6 headquarters at 54 Broadway, opposite St James’s underground station.

‘I was getting rather excited. I thought I might be going to be a spy, Mata Hari, seducing Prussian officers. But I don’t think either my legs or my German
were good enough because they sent me to the Government Code and Cypher School.’

She sat in London examining commercial codes and perusing the personal columns of
The Times
for coded spy messages, but in May 1940, after showing promise with a piece of smart lateral
thinking that uncovered the origin of an illegal shipment to Germany, Mavis was plucked out and sent to Bletchley to be the German linguist in Dilly’s new research team. His welcome was
typical of the way he threw new recruits in at the deep end and Mavis’s response immediately endeared her to him.

‘I reported to Commander Denniston and Barbara Abernethy, his secretary, took me over to see Dilly. He was sat by the window wreathed in smoke. He said: “Hello. Have you got a
pencil? We’re breaking machines.” I hadn’t a clue what he meant. He handed me a pile of utter gibberish and said: “Here, have a go.” It was covered in his purple inky
scrawls. “But I’m afraid it’s all Greek to me,” I said. Dilly burst into delighted laughter and said: “I wish it were.” I was very embarrassed later to discover
that he was a distinguished Greek scholar.’

There was more to Dilly’s choices than excluding any hint of masculine competitiveness from the research section. All the girls were carefully chosen for their capabilities. Commander
Denniston had picked Claire Harding for her administrative ability. Margaret Rock, the mathematician, and Mavis Lever, one of several German
linguists, were joined by speech
therapist Joyce Mitchell, and three actresses, all of whom were selected by Dilly because their training would give them an understanding of the rhythms of the messages. Mavis was adamant that it
was nothing to do with Dilly wanting to be surrounded by pretty young women. He was no womaniser.

‘He put women on pedestals. He was a great admirer of Lewis Carroll and for me Dilly was Alice’s White Knight, endearingly eccentric and always so concerned about one’s
welfare. The girls he chose had a background connected with linguistics or phonetics or literature. It was all a question of linguistic patterns of syllables for him. Others provided by Commander
Denniston had secretarial training and acted as registrars.’

Dilly had a unique knack of using his imagination to open up codes.

‘He would stuff his pipe with sandwiches instead of tobacco he was so woolly-minded. But he was brilliant, absolutely brilliant. It just seemed to come naturally to him. He said the most
extraordinary things. “Which way does the clock go round?” And if you were stupid enough to say clockwise, he’d just say: “Oh no it doesn’t, not if you’re the
clock, it’s the opposite way.” And that’s sometimes how you had to think about the machines. Not just to look at them how you saw them but what was going on inside. ’

Dilly’s unusual views on training left new recruits to sink or swim but ensured that Mavis, along with Margaret and the other girls, developed their ability to think laterally. Very often,
Dilly would sleep in the Cottage, working late into the night, surviving on black coffee and chocolate
and only returning to his home at Courns Wood, thirty miles south of
Bletchley, at the weekend. While the young girls were frustrated by Dilly’s inability to explain things simply, they clearly adored him, none more so than Mavis.

‘It was a strange little outfit in the Cottage. Organisation is not a word you would associate with Dilly Knox. I remember the amount of time we spent searching for his specs and tobacco
tin hidden under stacks of Enigma messages and how when preoccupied he mistook the cupboard for the door.’

The month after Mavis arrived, Italy entered the war and she was put to work on the Italian Navy’s Enigma code.

‘I had hardly begun to make head or tail of the Enigma codes and was doing the most menial tasks before Italy came into the war and I was put on to Italian, with only the scantiest
knowledge of the language and the tiniest pocket Italian dictionary to work with. So it was quite a challenge.’

Dilly was keen to find out if the machine the Italians were using was the same one that he’d broken in 1938, but because the Italian Navy was now dealing with naval movements across the
Mediterranean rather than just the Spanish Civil War, the messages were completely different and none of the ‘cribs’, the original text that Dilly had used before to break the code,
were of any use.

When he was breaking the Spanish and Italian Enigma machines in the 1930s, Dilly had devised a system of rods, strips of cardboard with a row of letters in the order they appeared in the wiring
of each Enigma rotor which were
slid along under the encoded text to try to find a point at which the text of the crib began to appear. It turned the complex task of
codebreaking into a word puzzle like a crossword, which Mavis found particularly easy.

‘Many of the girls never understood how the machine worked but they were excellent at rodding. We called it a game. It was like a game of Scrabble or like doing a crossword. But it did
require a lot of patience as there were seventy-eight positions to try out for the three rotors. You would have to work at it very, very hard and it made you pink-eyed. After you’d done it
for a few hours you wondered whether you’d ever see anything when it was before your eyes.’

The lack of cribs was a problem but when Dilly first broke the Italian Enigma all of the messages began with the Italian word
per
[for], to indicate who the message was for, so he told
the girls to look for a rodding sequence that would produce PER, plus an X, which was used to indicate a space between words. For three months, they tried to break the code without success. No one
could get PERX to fit. Then in September 1940, Mavis made the crucial breakthrough.

‘I was all on my own one night and I couldn’t put up PERX. It put up PER but not an X. It kept putting up an S. I thought, supposing it’s not PERX, it might be PERSONALE then
PER as in “personal for . . .” so I put up the rods for PERSONALE and then I got X and then PERX and then it went off beautifully all down the line.’

After a couple of spaces, she found there was a ‘GN’, which was the middle of SIGNOR, so she knew the two
missing spaces were SI and the three spaces
afterwards were OR and then X.

‘So I filled in my beautiful Italian crossword puzzle and when Dilly came in the next morning, I had the whole text of the message. He couldn’t believe it. Well, I couldn’t
believe it either because it was so easy, but it was simply because I was following Dilly’s methods.’

Dilly was impressed. He went to Commander Denniston and insisted Mavis must have a wage rise from 35 shillings (£1.75) a week, the rate for a temporary clerk, to the proper rate for a
linguist of 57 shillings and sixpence (£2.88). He also promoted her from the backroom to work with him in ‘the front room’ as one of his assistants along with Margaret Rock.

‘He took me out to dinner at the Fountain Inn on the Stony Stratford road to celebrate. It was my first experience of being driven in Dilly’s Baby Austin. Being driven anywhere by
Dilly was a nightmare, especially in the blackout. There were tank traps down Watling Street and he just drove straight through them. They were slightly shaken.’

Mavis was lucky with her billet. She was sent to a farm at Leighton Buzzard where the farmer’s wife immediately understood that the work Mavis and the other young women billeted with her
were doing was secret and she mustn’t ask any questions. She also seemed to realise that their work was important and appreciated the way that Mavis helped on the farm.

‘She would insist on bringing us a cup of tea in the morning. She suddenly said: “I shan’t be here next week. My aunt will be looking after you. I’m having a baby, you
know.” And we felt so awful that we’d let her wait on us. We had no idea and she laughed and just said: “You’re not the only ones who can keep a
secret, you know.”’

Working as one of Dilly’s assistants was very demanding, but also exhilarating. Mavis and Margaret had trouble keeping track of all the brilliant ideas he had to find ways into the
codes.

‘Dilly’s ideas just went off like a Catherine Wheel. He just had bright idea after bright idea. Margaret Rock would be trying to work out what he said yesterday and I’d be
trying to pin down something he said today and there were so many of these things that perhaps we had six bright ideas to work through and one of them would work. It was a strange form of lateral
thinking that brings in a lot of memory. But if he hadn’t had us to pin those bright ideas down for him I think perhaps it wouldn’t have worked so well.’

The problem with Dilly’s rods was that eventually the Italians would change the wiring of the rotors and the rods would be no use – they would no longer match the new configuration.
Then they would have to find out the wiring and create new rods, a complex task. The dreaded moment when they were no longer able to decode the messages came in November 1940. Fortunately, in order
to maintain a steady stream of messages so the Allies didn’t know that the sudden appearance of a long message meant something was about to happen, the Italians sent out a number of fake
messages, which Dilly called ‘duds’.

Mavis was working the night shift when she noticed there was something wrong with a message. They were so
used to looking for unusual things in messages that she spotted
immediately why it looked odd.

‘I picked up this message and thought: there’s not a single L in this.’