Alan Turing, the man who beat the Enigma code ... what was he like

A. Brilliant, kind, atheist, homosexual, polite. He also probably invented the computer.

Q. How

A. As a Cambridge graduate, he dreamed of an imaginary machine - a simple typewriter affair that could read instructions encoded on a tape and then carry out the sequential commands and modify its mechanical response accordingly. The idea was to replicate logical human thought.

Q. So he invented it

A. So many people have been involved in the computer revolution that it would be unfair to single out one man. But ... everyone who has used a PC is working on the evolution of a Turing Machine.

Q. That's what he called it

A. Yes. He launched the idea in an essay in Proceedings of the London Mathematical Society called On Computable Numbers, with an Application to the Entscheidungsproblem in 1937. It changed his life.

Q. Begin at the beginning.

A. Alan Mathison Turing was born in London in 1912, the second of two sons. His father was in the Civil Service in India, but the boys stayed in England with foster parents. Alan's loneliness during this time may have inspired his lifelong interest in how the human mind works. He was also greatly influenced by a popular book of that era called Natural Wonders Every Child Should Know. At 13 he went to Sherbourne School in Dorset and there showed a flair for mathematics.

Q. Anything else

A. Yes. He realised he was homosexual and fell in love with another boy, who suddenly died of tuberculosis. Turing's religious faith turned into atheism and the conviction that everything must have scientific explanations. If there was no soul, he thought, the body must be a machine.

Q. Acadaemia

A. Yes. He was made a fellow of King's College, Cambridge, and came under the guidance of John Maynard Keynes and E M Forster. After his degree he was invited to remain at King's as a tutor. And then came the Second World War.

Q. Codebreaking

A. Yes. Turing was recruited to serve in the Government Code and Cipher School, at Bletchley Park, Buckinghamshire. The task of all those assembled - including mathematicians, chess champions, Egyptologists - was to break the Enigma codes used by the Nazis in communications between headquarters and troops. Turing played a crucial role in designing a computer-like machine called the Bombe that could decipher, at high speed, Nazi codes to U-boats in the North Atlantic. This was incredibly secret - and the success of the codebreakers could not be made know. Churchill would not even fully share the results with the American allies, despite what Hollywood directors might say.

Q. So he was never really thanked publicly

A. No - not really until after his death. After the war, Turing returned to Cambridge, hoping to resume a quiet academic life. But he got involved in the creation of a Turing machine - the Automatic Computing Engine. The project was bogged down in red tape and he left for a more promising team at the University of Manchester. Soon, though, his private life ended in tragedy.

Q. What happened

A. Homosexuality was still an offence and he was prosecuted for gross indecency in 1952. On 7 June, 1954, he committed suicide by eating an apple injected with cyanide.

To ask a question about People & Places, click here

By Steve Cunningham