1.

Early Life & Education

Born in 1912 in London, Turing was raised with his brother by foster parents in Britain while his father worked in the civil service in colonial India. He was eventually sent to boarding school at the age of 13, where his immediate interest in mathematics and science singled him out in a traditional public school, whose ethos was still based on the teaching of classics and the rigours of the sports field.

Despite difficult school years which were clouded by the death of his great friend Christopher Morcom, he went on to study mathematics at King’s College, Cambridge, graduating in 1934. He completed his Masters three years later, by which time he was already elected a Fellow of his college on the strength of his undergraduate dissertation.  

His paper "On Computable Numbers, with an Application to the Entscheidungsproblem" was published in Proceedings of the London Mathematical Society in 1936 and has been called the most influential mathematics paper in history. He received his PhD from Princeton University in 1938, where he studied under Alonzo Church, who had also worked on the decidability of problems, publishing similar conclusions to Turing with different methods. Turing’s methods were simpler and more intuitive than Church’s and included the foundations of his ‘Turing machine,’ which is still a key idea in the theory of computation. 

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3.

Computers & Artificial Intelligence 

After leaving Bletchley Park, Turing turned his attention to what would become known as artificial intelligence. In 1945, he was recruited by the National Physical Laboratory (NPL) in London. He worked on the design of what would become the Automatic Computing Engine (ACE), the first electronic all-purpose digital computer. His plans imagined a fast computer with vast memory, but the engineering required to build it was considered too difficult and a much smaller computer was built instead.

The Turing Test

Turing eventually left the NPL to join the Computing Machine Laboratory at the University of Manchester, which was moving much faster to build innovative machines. While at Manchester, Turing created what has become known as the Turing test. In a paper published in Mind in 1950, he rejected the classic question “Can machines think?” and instead argued that a more useful metric was determining whether a machine was “intelligent” enough to fool a human into thinking it is a fellow human. This reframing of how we conceptualise intelligence—and the relationship between machines and humans—continues to guide discussions about artificial intelligence today. 

4.

Death & Legacy

Turing’s life was thrown off course when his house was burgled in January 1952. During the police investigation, he mentioned to police that he was in a relationship with a man named Arnold Murray, who was acquainted with the burglar. Both men were charged with gross indecency under Section 11 of the Criminal Law Amendment Act of 1885, which criminalised homosexuality. Turing’s own solicitor and his brother convinced him to plead guilty, which he did. Turing was ordered to undergo imprisonment or chemical castration; he chose the latter. He was given injections of oestrogen for one year, which were intended to reduce his libido and caused various side effects.  

A further consequence of this sequence of events was the removal of Turing’s security clearance, which was the general practice for known homosexuals at the time. He was unable to contribute to government work or to travel to the United States again. In June 1954, Turing was found dead in his home. The cause of death was cyanide poisoning, possibly from a half-eaten apple found nearby, which the inquest ruled as suicide. The true nature of his death, whether suicide or a tragic unintentional consequence of his experiments at home, is still ambiguous.   

In 2009, after an online petition to Parliament received over 30,000 signatures, Prime Minister Gordon Brown formally apologised to Turing for his treatment in the 1950s. In 2013, Queen Elizabeth II granted Turing a royal pardon. Turing’s work in mathematics, artificial intelligence and computing remains relevant to this day. He became more widely-known upon the release of the critically acclaimed film, The Imitation Game, starring Benedict Cumberbatch, in 2014. 

5.

On the Market

Turing’s enduring fame has fostered a strong market for Turing-related objects and documents in the UK and the US. The Imitation Game helped spread his story beyond the academic world to a mass audience. Most Turing-related items sell for over £5,000. Because he only published in niche academic journals and remained unknown outside the academic world during his lifetime, materials related to him are rare. Even a copy of the programme to the “Manchester University Computer Inaugural Conference, July 1951”, which Turing helped organise and contributed towards, makes £2,000 upwards. Books by other authors that were owned by Turing have made between £4,000 and £15,000, each depending on how significant they are deemed to be in relation to his career.  

The quality of the item and closeness of its relationship to Turing make a big difference in its valuation. Bonhams has seen some fantastic results in this market. One copy of an autograph letter signed ("Yours Alan") to Alfred William Beuttell, returning his notes on the Monte-Carlo system " was sold at Bonhams for £94,000. Another copy that was inscribed and a specifically printed “off-print” with good provenance sold for £205,250. One of his composition notebooks sold for $1,025,000 in 2015. In 2017, an autograph letter signed ("A.M. Turing"), to his former mathematics teacher D.B. Eperson sold for £75,000.