Codebreaker Alan Turing new face of £50 note

Announcing the decision, Bank of England governor Mark Carney said: “Alan Turing was an outstanding mathematician whose work 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.”

Turing devised code breaking machines during the war, and his groundbreaking research paved the way for the modern computer.

But his career and life were curtailed in 1952, when he was convicted of gross indecency over his relationship with a man. He accepted probation on the condition he receive the hormone oestrogen, otherwise known as chemical castration. He was also banned from consulting with GCHQ, as homosexuals were ineligible for security clearance.

Two years later he died by suicide. He was received an official apology in 2009 and a royal pardon in December 2013. The Alan Turing Law, passed in 2017, pardons all men cautioned or convicted under old laws that outlawed homosexual acts.

The design of the reverse of the new polymer £50 note will feature a photo of him and a table and formulae from his 1936 paper, On Computable Numbers, with an Application to the Entscheidungsproblem. The seminal paper is widely acknowledged as being the foundation for all future computer science.

The note will also feature Turing’s date of birth – 23 June 1912 – in binary code, and his signature from the visitor’s book at Bletchley Park, where he worked during WW2.

Turing was one of a number of figures from the world of science nominated by the public. The Banknote Character Advisory Committee then drew up a shortlist of 12, which included Mary Anning, Stephen Hawking, Ada Lovelace and Charles Babbage as well as Turing. The final decision was made by Carney.

The note is expected to enter circulation by the end of 2021.