During the Second World War, Turing worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain’s codebreaking center that produced Ultra intelligence. For a time he led Hut 8, the section that was responsible for German naval cryptanalysis. It was here, where he devised a number of techniques for speeding the breaking of German ciphers, including improvements to the pre-war Polish bombe method, an electromechanical machine that could find settings for the Enigma machine.
Turing played a pivotal role in cracking intercepted coded messages that enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic, and in so doing helped win the war. At the upper end it has been estimated that this work shortened the war in Europe by more than two years and saved over 14 million lives.
In 1952, Turing was arrested for homosexual acts; the Labouchere Amendment had mandated that “gross indecency” was a criminal offence in the UK. He accepted chemical castration treatment, with DES, as an alternative to prison.
Turing died in 1954, 16 days before his 42nd birthday, from cyanide poisoning. An inquest determined his death as a suicide, but it has been noted that the known evidence is also consistent with accidental poisoning.
Now the Bank of England has announced, in what completes the official rehabilitation of Turing, will be the face of the new £50 note.
The Banks’ governor Mark Carney said: “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 war hero, Alan Turing’s contributions were far ranging and path breaking. Turing is a giant on whose shoulders so many now stand.”
The Bank acknowledged Turing’s pivotal role in the development of early computers, first at the National Physical Laboratory and later at the University of Manchester.
“He set the foundations for work on artificial intelligence by considering the question of whether machines could think,” the Bank said. “Turing was homosexual and was posthumously pardoned by the Queen having been convicted of gross indecency for his relationship with a man. His legacy continues to have an impact on both science and society today.”
Turing’s face will appear on the new £50 polymer note when it goes into circulation in 2021 following a public consultation process designed to honour an eminent British scientist.