Turing proposed the concept of an automatic machine (Turing machine) capable of simulating any algorithm to determine a result from any input; this can be considered a model of a computer. During the Second World War, he played a pivotal role in cracking the German Enigma code and providing the Allied Forces with intelligence contributing to major victories, including in the Battle of the Atlantic, shortening the war by an estimated two years and potentially saving 14 million lives.
Following the war, he worked on early designs for computers in Manchester and established artificial intelligence as a theoretical field. He was prosecuted for same-sex acts in 1952, leading to his chemical castration and subsequent (likely) suicide.
Decades later, Turing has been selected as the face of the new £50 note following a painstaking ‘character selection process’, which involved the Banknote Character Advisory Committee narrowing down 989 different nominated characters to a shortlist of 12 options through consultation with experts. The shortlist was comprised of extraordinary British scientists, including 19th Century computing pioneers Charles Babbage and Ada Lovelace.
“The strength of the shortlist is testament to the UK’s incredible scientific contribution,” said Chief Cashier Sarah John. “The breadth of individuals and achievements reflects the huge range of nominations we received for this note and I would like to thank the public for all their suggestions of scientists we could celebrate.”
The final decision was made by Mark Carney, Governor of the Bank of England.
Speaking at the Science and Industry Museum in Manchester, 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.”
Manchester Lib Dem leader John Leech, who led the Parliamentary effort to pardon Turing, wrote on Twitter: “Very emotional seeing [the banknote design] for the first time today – genuinely over the moon that Turing has been chosen as the face of the £50 note. A massive acknowledgement of his mistreatment and unprecedented contribution to society.”
Following the announcement, Manchester Central Labour MP Lucy Powell tweeted: “Absolutely delighted by this news. Alan Turing was a national hero and treasure who suffered disgusting prejudice for his sexuality. It’s absolutely right we celebrate him for who he was.”
The new £50 will be a long-lasting polymer note, and is expected to enter circulation by the end of 2021.
A concept image of the note depicts: a 1951 photograph of Turing; his signature; details from his epoch-making 1936 paper, On Computable Numbers; an image of the automatic computing engine designed by Turing and built at the National Physical Laboratory; technical drawings for the Bombe (the machine used to break coded messages); ticker tape depicting Turing’s birth date in binary code; and a 1949 quote from Turing (“This is only a foretaste of what is to come, and only the shadow of what is going to be”).
Turing’s contributions to the war effort and to computer science went unrecognised for many decades. The publication of Andrew Hodges’ Alan Turing: The Enigma in 1983 brought to light his enormous contributions to the modern world. He has since been commemorated in numerous books, films, plays, and was granted a posthumous pardon by the Queen in 2013. In February, he was voted the ’ultimate icon’ of the 20th Century by BBC viewers.