Alan Mathison Turing spent most of his childhood in Hastings, where his parents left him and his brother with a retired Army couple, Colonel and Mrs Ward, in a large house, Baston Lodge, Upper Maze Hill, St Leonards on Sea, while his father worked as a colonial administrator in Madras, India. Nearby was the house of Sir Henry Rider Haggard, the author.

He was sent to boarding school, Sherborne, Dorset, and in 1931 studied mathematics at King's College, Cambridge, being elected a Fellow at the age of only 22. In the same year he invented the abstract computers now known as Turing machines on which all subsequent stored-program digital computers are modelled.

Working independently, Turing and Alonzo Church in the US both showed in 1936 that there are well-defined mathematical problems that cannot be solved by effective methods. This expanded on the work of the Austrian logician Kurt Godel published in 1931, that there can be no consistent, complete formal system of arithmetic.

During 1936-1938 Turing continued his studies at Princeton University. He completed a PhD in mathematical logic under Church's direction, analysing the notion of 'intuition' in mathematics and introducing the idea of oracular computation in mathematical recursion theory.

At the outbreak of war in 1939 he joined the Government Code and Cypher School at Bletchley Park, Buckinghamshire. Building on earlier work by Polish cryptanalysts, Turing contributed crucially to the design of electro-mechanical machines ('bombes') used to decipher the German 'Enigma' code and also worked on the 'Fish' codes. Turing received the OBE for his wartime work.

In 1945, Turing was recruited to the National Physical Laboratory in London, to design and develop an electronic computer. The Automatic Computing Engine (ACE) was the first relatively complete specification of an electronic stored-program general-purpose digital computer. The first working computer however was built by the Royal Society Computing Machine Laboratory at Manchester University, where Turing became effectively Director in 1948. Turing was elected a Fellow of the Royal Society in 1951.

In March 1952 however he was prosecuted for homosexuality, then a crime in Britain, and sentenced to a period of twelve months hormone 'therapy'. This and other pressures, such as loss of security clearance, led to his suicide two years later, by eating from an apple laced with cyanide. An 'apology' for his treatment was issued by the Prime Minister in 2009.

Memorials of Turing have been put up in recent years: in Sackville Park, Manchester, 2001, on the University of Surrey campus, 2004, and at Bletchley Park, 2007.

The Alan Turing Home Page, by Andrew Hodges (biographer).

Quockling, on Turing in Hastings, by Dean Morrison.

Turing Archive: for the History of Computing.

Guardian,
Article about Turing commemorations.