Alan Turing, the British mathematician, code-breaker and computing pioneer who was hounded to suicide after being convicted under anti-LGBTQ+ legislation, has been chosen to appear on the reverse of the new polymer £50 note, due to enter circulation at the end of 2021.
Born in 1912, Turing attended the University of Cambridge, where he was a student of Austrian philosopher Ludwig Wittgenstein, and later obtained his PhD from Princeton in the US, where he worked on some of the most fundamental underpinnings of modern-day computing.
At the outbreak of the Second World War, he was attached to the Government Code and Cypher School (GC&CS) at Bletchley Park in Buckinghamshire (pictured above), where he worked on cryptanalysis, developing the famous Bombe machines that were instrumental in helping crack Nazi Germany’s Enigma code, an act that is estimated to have dramatically shortened the length of the war.
After 1945, he worked on developing some of the earliest true computers, and helped set out the foundations for present-day work on artificial intelligence (AI) and data science.
However, as a gay man at a time when this was illegal in the UK, Turing fell afoul of the law and in 1952 was prosecuted and convicted of “gross indecency”. He chose to accept chemical castration instead of a prison sentence, and was also stripped of his government security clearance and barred from his ongoing work with the intelligence services. In 1954, just short of his 42nd birthday, he died of cyanide poisoning. At inquest, his death was ruled a suicide.
It took until 2009 for Turing to receive an official apology from then prime minister Gordon Brown, and 2013 for him to be granted a posthumous pardon by the Queen. As of 2017, the Alan Turing Law, an amendment to the Policing and Crime Act, retroactively pardoned men convicted or cautioned under historical anti-LGBTQ+ legislation in England and Wales.
“Alan Turing was an outstanding mathematician whose work has had an enormous impact on how we live today,” said Bank of England governor Mark Carney. “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.”
Besides a picture of Turing, based on a 1951 photo housed at the National Portrait Gallery, the design of the note will feature a table and formulae from his 1936 paper, On computable numbers, with an application to the Entscheidungsproblem, which introduced the concept of the so-called Turing machine as a future operable computer; the Automatic Computing Engine (ACE) pilot, developed at the National Physical Laboratory in Teddington as a trial model for an electronic stored-program digital computer; technical drawings for the code-breaking Bombe; Turing’s signature, taken from the Bletchley Park visitor book; ticker tape depicting Turing’s birthdate, 23 June 1912, in binary; and a quote given by Turing in a 1949 Times interview, “This is only a foretaste of what is to come, and only the shadow of what is going to be”.
The Bank of England chose to celebrate the field of science and technology on the new note, and received 227,299 nominations for 989 eligible people during a six-week public nomination period in 2018.
Besides Turing, the final shortlist of nominees included Mary Anning, Paul Dirac, Rosalind Franklin, William and Caroline Herschel, Dorothy Hodgkin, Ada Lovelace and Charles Babbage, Stephen Hawking, James Clerk Maxwell, Srinivasa Ramanujan, Ernest Rutherford, and Frederick Sanger.
“The strength of the shortlist is testament to the UK’s incredible scientific contribution. The breadth of individuals and achievements reflects the huge range of nominations we received for this note and I would to thank the public for all their suggestions of scientists we could celebrate,” said the Bank of England’s chief cashier, Sarah John.
The current £50 note, which has been in circulation since 2011, features Scottish inventor James Watt and his business partner Matthew Boulton, who kick-started the Industrial Revolution and cemented over a century of British commercial dominance with the development of the first practical steam engine in 1776.