Alan Turing: The New Face of the £50 Note

July 1, 2021| Previous Issue

By Alex Rose

Many people know Alan Turing’s story, but did you know that he lived in Guildford? As the new £50 notes featuring Turing begin to roll out, let’s take a look at his life and ties to the Guildford area.

On the 23rd of June, Alan Turing’s birthday, the new polymer £50 note entered circulation. The design on the note honours Turing’s revolutionary work at Bletchley Park in the second world war in decrypting Nazi Germany’s Enigma machine and pioneering the field of study that would eventually develop computers. So, how and why has his life been celebrated in the newest banknote?

Born in 1912 in London, English mathematician Alan Turing grew up in Guildford and later attended King’s College, Cambridge and earned a degree in mathematics. He also attended Princeton University, USA, where he obtained his PhD. Aside from his remarkable talents in mathematics, science and cryptography, he was an Olympic level runner, completing a number of marathons and running great distances every day. He grew up very self-reliant and didn’t fit in with fellow students, although he was greatly affected by the death of his close friend Christopher Morcom, with whom he worked together on scientific ideas. This was his first close friendship, and the sudden loss was devastating.

The design on the new £50 note honours Turing’s revolutionary work at Bletchley Park in the second world war in decrypting Nazi Germany’s Enigma machine and pioneering the field of study that would eventually develop computers.

Alan wanted to believe that Christopher’s spirit lived on, which inspired the foundation of Turing’s later work involving a strong interest in the mind. This later manifested in his concept of the universal machine, which could solve any mathematical problem, much like the human brain. This idea eventually evolved into modern day computers.

Bletchley Park was shrouded in the highest levels of secrecy during World War II and beyond, as it housed those whose job it was to intercept enemy radio signals, decode them and deliver the intelligence to the military and government. They recruited those with the strongest problem-solving skills by attracting candidates using cryptic crossword puzzles. On the 4th of September 1939, Turing and a handful of other mathematicians, linguists and chess champions were recruited into Bletchley park and he soon became the head of the Naval Enigma Team, working in Hut 8. Their job was to decipher the daily communications intercepted from Nazi Germany and their allies encrypted through the use of the Enigma machine. This device allowed complex message encoding which changed on a daily basis. Although the ever-changing code was initially thought impossible to crack, Turing led the team responsible for analysing the enciphered messages, which held critical information of secret Nazi military operations.

While others in his team attempted to break the code using traditional means, Turing soon realised that only a machine would be able to compute the vast number of possible combinations in the time required. He and his colleague Gordon Welchman designed and built the Bombe, an electro-mechanical device used to successfully break the enigma codes. Vast amounts of priceless information about enemy operations were gained through the use of this machine, which shortened the war by an estimated two years, saving countless lives.

A replica of the Bombe.

The reverse of the new polymer £50 note showing Turing, some of his calculations and a depiction of the Bombe.

The reverse of the new £50 note, released on the 23rd of June 2021 features a design composed of a picture of Alan Turing – based on the photo owned by the National Portrait Gallery – as well as images of a matrix table, binary code, Bombe technical drawings and a mathematical formula. It also features Turing’s signature, taken from the signature book on display at Bletchley Park Trust. The note itself retains its deep red colour and, as ever, the queen’s face.

The quote on the new £50 note was taken from an interview, where Turing said, “This is only a foretaste of what is to come, and only the shadow of what is going to be.”

His life in Guildford is attested to by the blue plaque at 22 Ennismore Avenue (although it was number eight when he lived there), where his parents moved from London to raise him and his brother in 1927. His family would regularly visit the nearby Stoke Park, which they lived next to, by going on long walks there, and at the North Downs. Alan would also go on to use Stoke Park as a frequent running spot. Astronomy interested him when he lived here, and he found that the Guildford skies were excellent for stargazing. John Turing, Alan’s brother, even married at St John’s Stoke Church. After his parents separated, his father relocated to London, whilst his mother stayed in Guildford, moving to Epsom Road and then South Hill, where Alan would visit, going on long walks with her, where they discussed his work. A statue of Turing was raised on the Surrey University campus to memorialise him in 2004.

The plaque on the house originally owned by Turing’s parents.

Alan Turing’s statue at the University of Surrey in Guildford (surrounded by COVID measures).

Needless to say, without Turing, we wouldn’t have modern computers. He founded an entire field of study and saved the lives of many thousands in the war. Turing died in 1954 by suicide, after being sentenced to hormone therapy – by the same government he helped to win a war – to ‘cure’ his homosexuality. He was cremated at Woking Crematorium, and his ashes were spread where his father’s had been. In 2013, the queen signed a royal pardon for Turing’s conviction. The quote on the new £50 note was taken from an interview, where he said, “This is only a foretaste of what is to come, and only the shadow of what is going to be.”

Alan Turing was shaped, in part, by his life in Guildford, and went on to achieve great things, which have impacted all of us. I believe this is something that we can all feel connected to and proud of.