Alan Turing

Recruitment and Bletchley Park

He was born on 23 June 1912 in Maida Vale, London. He was recruited in 1938 and, after specially devised courses, joined GC&CS, the forerunner of GCHQ, at Bletchley Park in September 1939.^1,2

In January 1940 he met Polish cryptologists in Paris (see Breaking Enigma), who – as GCHQ puts it – gave him the insights he needed to design the Bombe. It was the first special-purpose British cryptanalytic machine and helped exploit German Naval Enigma.^1,2

During the war he was one of Bletchley Park’s leading cryptanalysts and spearheaded the effort in Hut 8 against German Naval Enigma. Later he moved on to secure speech systems.^1,2

After the war

In 1946 he was appointed OBE, and on 15 March 1951 he was elected a Fellow of the Royal Society.³

From 1948 to 1954 he worked at the University of Manchester on the Manchester Mark 1 computer. GCHQ notes that he and Max Newman led the team that produced Britain’s first general-purpose stored-programme computer (the Ferranti Mk 1).^1,4

Conviction and death

In March 1952 he pleaded guilty and was convicted of gross indecency – homosexual activity, then illegal. Instead of prison he chose hormone injections, which the British government in a 2013 announcement called chemical castration.^2,4,5

He died in June 1954 in Wilmslow; GCHQ writes that he took his own life.^2,3

Apology, pardon and remembrance

In September 2009 Prime Minister Gordon Brown apologised on behalf of the government for the way Turing had been treated.⁴

On 24 December 2013 the Queen, at the request of the Justice Secretary, Chris Grayling, granted him a posthumous pardon under the Royal Prerogative of Mercy.⁵

On 23 June 2021, his birthday, a Bank of England polymer £50 note bearing his portrait entered circulation.⁶