Work on breaking the Enigma code had started long before the war, and cryptographers from all over Europe including Poland, had done the ground work. Turing's work on Enigma was greatly helped in May 1941 by the lucky capture of an Enigma machine from a German U-boat, which pushed the project forward by several years. <ref> http://ww2today.com/9th-may-1941-enigma-machine-captured</ref>
In the later part of WW2, because of the capture of the Enigma machine, the Nazis shifted from using the Enigma code to using a far more fiendish complicated one. They called it the Lorenz cipher and the Bletchley control nicknamed it Tunny, or the Fish. While the Enigma code machine had only three wheels, the Tunny machine had twelve, and had other random tricks built into it to make decoding so difficult that even a mathematician could hardly calculate all the possible combinations. The code changed with every letter of the same message. In the later part of the war, from 1943 onwards, Tunny, not Enigma, was the code that the Germans depended on for their top-most secrets and attack plans. Tutte and Flowers worked on breaking the Tunny code.
[[Bill Tutte]], the principal mathematician who undertook the work on Tunny, came from a humble background, being the son of a gardener and a cook, and he went to a grammar school - unlike Turing who had been to an elite private school. From there Tutte won a scholarship to university where he studied chemistry. He was aged only 24 when he arrived at Bletchley. His feats of deduction and analysis were extraordinary and have been described as a "miracle". Because the sheer quantity of data to be processed was overwhelming, Professor [[Max Newman]] suggested that they try to build a calculating machine along the lines suggested by Turing. Turing took no other part in the Tunny project. Turing's first machine did not work very well and the successful machine, "Colossus" was built by [[Tommy Flowers]]. He was a Post Office telephone engineer from a working-class background. He used electric circuits and valves. Because all this work was top secret, even after the war ended, neither of them could talk about what they had done or get credit for it. Unlike Turing, these "unsung heroes" have no statues put up to them, because they are [[heterosexual]].