The mathematician’s stature has grown steadily since the 1980s, as a brilliant, socially misunderstood scientist

Bank of England

When the new red polymer £50 note is presented to Queen Elizabeth II and circulated to the British public in 2021, it will be Britain’s first coin of the realm to bear the picture of a Princeton graduate: mathematician Alan Turing *38. Turing’s stature has grown steadily since the 1980s, as a brilliant, socially misunderstood scientist, cause célèbre of the gay-rights movement, with the added piquancy of his suicide at the age of 41. Was it really a suicide, as his mother questioned, or a tragic accident? The uncertainty adds even more poignancy to the life of this British hero. 

Turing was chosen as the face of the new British note after the Banknote Character Advisory Committee – including Princeton history professor David Cannadine – decided in 2018 to honor the field of science. The Bank of England received more than 250,000 nominations from the British public involving 989 eligible individuals, who included such notables as physicist Stephen Hawking, mathematician and engineer Charles Babbage, and chemist Rosalind Franklin. After considerable deliberation, the committee selected a shortlist of 12 scientists; Mark Carney, then governor of the Bank of England, selected Turing. “As the father of computer science and artificial intelligence, as well as war hero, Alan Turing’s contributions were far-ranging and path-breaking,” Carney said in announcing the decision. “Turing is a giant on whose shoulders so many now stand.” 

Turing’s now-legendary status as a cryptographer, leader in the worlds of math and, later, of biology, and one who was totally indifferent to the formalities of everyday life emerged gradually in the 1970s and ’80s. His portrayal in the 2014 film The Imitation Game as a tortured genius with a rude disposition was exaggerated, according to those who knew him. Michael Ramsbottom, a Bletchley Park colleague who studied with Turing at Cambridge, says he found Turing “shy and polite socially.” 

According to Alan Turing’s nephew Dermot Turing, who is also his biographer, the victim role history seems to have assigned his uncle is incorrect: Alan’s father held a high-ranking government position in India, which conveyed entitlement and privilege. “Alan was imperious, sometimes patient; invariably generous; often witty and sometimes biting; awkward in company not involving his peers.”

Under the Official Secrets Act, much of Turing’s covert work during World War II remained illegal to discuss until the 1980s. Indeed, Turing’s work – inventing machines that cracked the seemingly impenetrable German code – wasn’t explained until Andrew Hodges’ 1983 book The Enigma, and then information trickled forth in publications, documentaries, and a play, Breaking the Code.

Turing was attracted to Princeton because the University and the nearby Institute for Advanced Study housed the greatest assembly of mathematical minds in the world. He was awarded his Ph.D. after only two years at the Graduate College – an impressive achievement. The looming spectre of Nazism and Britain’s inevitable war with Germany overshadowed his years on campus. Turing had one eye on returning home to support the war effort despite his close relationship with perhaps the world’s greatest mathematician, John von Neumann, then at the Institute for Advanced Study, who offered him a job. He declined.

His nephew says a coolness existed between Turing and his Princeton Ph.D. supervisor, the sartorially and socially fastidious Alonzo Church. When interviewed by the historian William Aspray, Church was diffident about his brilliant pupil, who could appear dishevelled and as an erratic thinker: “I had a lot of contact with him. I discussed his dissertation with him rather carefully.” Of Turing’s personality, Church said: “I did not have enough contact with him to know. He had the reputation of being a loner and rather odd.”

“Princeton would have suited him very well,” Dermot Turing observes. “It was an enclosed academic world, the perfect place to work, but there was culture shock. Church had beaten him to publishing a complex mathematical question although they had both solved it simultaneously, and he’d had to learn a new mathematical language, lambda-calculus. 

Ultimately, Turing’s work during the war led to the development of the machinery and methodology of the prototypes of modern computers. After the war he moved to the University of Manchester, where he engaged in innovative biological research. In 1951, he published a study that used equations to show how chemicals are used in the developmental life of an organism.

The question of Turing’s homosexuality and suicide weeks short of his 42nd birthday has sparked many reactions in Britain, especially shame over the way he was treated. In 2013 Queen Elizabeth signed a pardon for Turing’s conviction for gross indecency. Until 1967 homosexuality was a criminal offense, but it was not very hidden or scandalous in aristocratic or establishment circles. Turing’s mistake was in getting caught: He reported a burglary perpetrated by a man with whom he’d had a relationship; the man then confessed the nature of his relationship with Turing to the police. Turing avoided jail by agreeing to submit to hormone injections that reduced his libido and caused him to gain weight and grow breasts. By doing this, he was able to keep his academic job.

Some have challenged the inquest’s determination that Turing committed suicide by ingesting cyanide in a half-eaten apple found at his bedside, as the apple was never tested for traces of cyanide. Leading the cry for a verdict of accidental death was Turing’s mother, whom he disliked: She wrote that Turing had been in good spirits, had recently bought new clothes and had accepted future invitations, and had been conducting experiments with cyanide in his room. Other family members and friends accepted the inquest’s finding and believed Turing was taking charge of his life. 

Dermot Turing says research on his uncle’s life remains to be done. Princeton has been mentioned in news coverage of the Turing banknote – part of the history of one of Britain’s greatest war heroes and mathematicians.  

London resident Genevieve Muinzer ’75 is the founder of AdAstra Films and Media and former editor of the magazine of The Prince’s Foundation.