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themselves—to deduce the wiring of two wheels of the German plugboard Enigma machine.
Twinn, a mathematician who had been recruited to Dilly’s permanent staff from Brasenose
College, Oxford, in February 1939, was very familiar with Knox’s methods. The next section
(The race to break Enigma) tells the story of the monster crib that Twinn used to crack the
wheels.
It was later in the autumn of 1939 that Turing began his attack on the German Naval Enigma,
which nobody was tackling. He worked in the stable-yard cottage that Dilly had chosen in order
to be away from the administrators in the Mansion (Fig. 11.2). Dilly, like Turing, was a loner.
The cottage was very cramped downstairs, and Turing elected to go into the loft above. Since the
only access was a ladder in the wall, two of the girls rigged up a pulley and basket for sending up
coffee and sandwiches. Typically, Turing did not wish to come down and socialize.
I arrived as a German linguist from University College, London, in April 1940. By this time
the Hut system was in full swing. Turing’s first bombe was just going into action against Naval
Enigma, and he was now head of Hut 8, the Naval Enigma Section. Dilly was in the Cottage,
working on still unbroken versions of the Enigma machine. I was taken over to the Cottage and
introduced to him. He looked up, amid wreaths of pipe smoke, and said to me ‘Hello, we are
breaking machines—have you got a pencil?’.
figure 11.2 Cottage 3 with Turing’s stable lads’ loft.
Reproduced with permission of Peter Fox.