a father of computer science. A fellow of King’s College, Cambridge from 1935, in 1936 he wrote his seminal paper ‘On Computable Numbers’ (1936), which introduced the Turing Machine as an aid to a precise definition of the concept of the algorithm. During World War II Turing worked at the British government’s code-breaking centre at Bletchley Park. He was instrumental in breaking the German Enigma codes, designing an electromechanical machine to assist this process. After the war he worked at the National Physical Laboratory, where he designed (1945–6) the ACE, an early stored-program computer. His paper ‘Computing Machinery and Intelligence’ (1950), which introduced the Turing test, remains a foundation of artificial intelligence. In 1952 Turing was convicted following a homosexual affair (then illegal in Britain) and submitted to ‘treatment’ for his homosexuality. He died of cyanide poisoning, officially by suicide, although the exact circumstances remain unclear. In 2013, following an Internet campaign, he was granted a posthumous pardon.