While at the Intelligence Centre, Bletchley Park, Alan came up with ways to break German ciphers, including improvements to pre-Second World War Polish methods for finding the settings for German Enigma machines.
“Alan Turing was an outstanding mathematician whose work has had an enormous impact on how we live today. As the father of computer science and artificial intelligence, as well as a war hero, Alan Turing’s contributions were far ranging and path breaking. Turing is a giant on whose shoulders so many now stand.”
Prosecuted for homosexual acts in 1952, Alan was convicted and given a choice between imprisonment and probation which was conditional on his agreement to undergo hormonal physical changes designed to reduce libido. He accepted the option of injections of what was then called stilboestrol, a synthetic oestrogen and this his feminization of his body was continued for the course of one year. It rendered him impotent and created breast tissue and thus fulfilled, in the literal sense, his prediction that "no doubt I shall emerge from it all a different man, but quite who I've not found out".
His criminal conviction destroyed part of his career with the removal of his security clearance which barred him from continuing with his cryptographic consultancy for the Government Communications Headquarters (GCHQ), though he kept his academic job. An inquest concluded that Alan's death from cyanide poisoning two years later was suicide
John Leech, the former Liberal Democrat MP for Manchester Withington who helped lead the campaign for a 'Turing Law', said he was “very emotional” to see the new £50 note at the official unveiling and that it was a “massive acknowledgement of his mistreatment and unprecedented contribution to society. It is almost impossible to put into words the difference that Alan Turing made to society, but perhaps the most poignant example is that his work is estimated to have shortened the war by four years and saved up to 21 million lives. And yet the way he was treated afterwards remains a national embarrassment and an example of society at its absolute worst.”
Alan's work helped cement the concept of the algorithm, the set of instructions used to perform computations that are at the heart of our relationship with computers today. He was also a pioneer in the field of artificial intelligence: one of his best known achievements in this field is the 'Turing Test', which aims to measure whether a machine is 'intelligent'.
His words on the banknotes appear in the form of a quote he gave to the Times in 1949 :
Just six years ago, in 2013, Alan was given a 'posthumous royal pardon' by the Queen for his 1952 conviction for gross indecency.
The Imitation Game : https://www.youtube.com/watch?v=xlsFwBhiY-M