The UK's new £50 note has entered circulation on the 109th anniversary of the birth of its subject, the mathematician and computer scientist Alan Turing.
Initially announced two years ago, and unveiled back in March, the note is due to become available in bank branches and ATMs over the coming days.
Its arrival completes the Bank of England's range of polymer notes, and the clock is ticking down to 30 September 2022, at which point the previous paper versions of the £20 and £50 notes cease to be legal tender (although it is expected that deposits using the older notes will be still be accepted.)
As for the £50 note itself, the photo of Turing was snapped in 1951 by photography studio Elliott and Fry. Also visible in the design is an image of the Automatic Computing Engine (ACE), as well as technical drawings for the Bombe, one of the tools used to break Enigma-enciphered messages in World War II.
A working reconstruction of the Turing-Welchman Bombe is on display at The National Museum of Computing, which is showing off the new note alongside, as well as a Snapcode that will allow an Augmented Reality experience with the note.
Away from AR fun and games, ticker tape showing Turing's date of birth in binary flows over the note and a mathematical table from his 1936 paper "On Computable Numbers, with an application to the Entscheidungsproblem" [PDF] is visible.
Turing's 1949 quote "This is only a foretaste of what is to come and only the shadow of what is going to be" is shown beneath his image. The signature on the note is from the visitor's book at Max Newman's house.
CEO of the National Physical Laboratory (NPL), Dr Peter Thompson, said: "Alan Turing's time at NPL and the development of the pilot ACE are an important part of NPL's scientific history. Turing's initial design was drawn up in 1945 and approved by the NPL in 1946. The computer ran its first program in 1950, after Turing had departed NPL for Manchester University.
Thompson went on to thank the Bank of England for depicting Turing and the ACE on the note: "For any organisation, scientific or other, fostering a diverse and inclusive workforce creates an environment where innovation thrives and everybody feels safe and secure in their workplace."
The appalling treatment of Turing himself, simply due to being gay and despite his astonishing and celebrated wartime efforts, is well-documented and he was found dead on 8 June 1954 from cyanide poisoning. Turing was persecuted by the state for his homosexuality and was convicted of gross indecency in 1952.
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He was eventually granted a posthumous pardon in 2013 following an apology from the UK Prime Minister in 2009.
Speaking at Bletchley Park, Governor of the Bank of England Andrew Bailey said: "Placing him on this new banknote is a recognition of his contributions to our society, and a celebration of his remarkable life." ®