WWII code breaker Alan Turing to be the face of new £50 note

Alan Turing, who is best known for devising code-breaking machines during World War Two, is set to appear on the new £50 note, the Bank of England has announced.

The Bank of England chose Turing following a selection process which included advice from scientific experts.

During the Second World War, Turing worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain’s codebreaking centre that produced Ultra intelligence.

For a time he led Hut 8, the section that was responsible for German naval cryptanalysis.

Here, he devised a number of techniques for speeding the breaking of German ciphers, including improvements to the pre-war Polish bombe method, an electromechanical machine that could find settings for the Enigma machine.

In 2018, the Banknote Character Advisory Committee chose to celebrate the field of science on the £50 note and this was followed by a six week public nomination period.

The Bank received a total of 227,299 nominations, covering 989 eligible characters.

The Committee considered all the nominations before deciding on a shortlist of 12 options, which were put to the Governor for him to make the final decision. 

Mark Carney, Governor of the Bank of England, commented: “Alan Turing was an outstanding mathematician whose work has had an enormous impact on how we live today. As the father of computer science and artificial intelligence, as well as war hero, Alan Turing’s contributions were far ranging and path breaking. Turing is a giant on whose shoulders so many now stand.” 

Alan Turing provided the theoretical underpinnings for the modern computer. While best known for his work devising code-breaking machines during WWII, Turing played a pivotal role in the development of early computers first at the National Physical Laboratory and later at the University of Manchester.

He set the foundations for work on artificial intelligence by considering the question of whether machines could think. Turing was homosexual and was posthumously pardoned by the Queen having been convicted of gross indecency for his relationship with a man. His legacy continues to have an impact on both science and society today. 

The shortlisted options demonstrate the breadth of scientific achievement in the UK, from astronomy to physics, chemistry to palaeontology and mathematics to biochemistry.

The shortlisted characters, or pairs of characters, considered were Mary Anning, Paul Dirac, Rosalind Franklin, William Herschel and Caroline Herschel, Dorothy Hodgkin, Ada Lovelace and Charles Babbage, Stephen Hawking, James Clerk Maxwell, Srinivasa Ramanujan, Ernest Rutherford, Frederick Sanger and Alan Turing.

Sarah John, Chief Cashier, said: “The strength of the shortlist is testament to the UK’s incredible scientific contribution.  The breadth of individuals and achievements reflects the huge range of nominations we received for this note and I would to thank the public for all their suggestions of scientists we could celebrate.” 

The new £50 note will celebrate Alan Turing and his pioneering work with computers. As shown in the concept image, the design on the reverse of the note will feature:

• A photo of Turing taken in 1951 by Elliott & Fry which is part of the Photographs Collection at the National Portrait Gallery.
• A table and mathematical formulae from Turing’s seminal 1936 paper “On Computable Numbers, with an application to the Entscheidungsproblem” Proceedings of the London Mathematical Society. This paper is widely recognised as being foundational for computer science.  It sought to establish whether there could be a definitive method by which any theorem could be assessed as provable or not using a universal machine. It introduced the concept of a Turing machine as a thought experiment of how computers could operate.  
• The Automatic Computing Engine (ACE) Pilot Machine which was developed at the National Physical Laboratory as the trial model of Turing’s pioneering ACE design. The ACE was one of the first electronic stored-program digital computers.
• Technical drawings for the British Bombe, the machine specified by Turing and one of the primary tools used to break Enigma-enciphered messages during WWII. 
• A quote from Alan Turing, given in an interview to The Times newspaper on 11 June 1949: “This is only a foretaste of what is to come, and only the shadow of what is going to be.”
• Turing’s signature from the visitor’s book at Bletchley Park in 1947, where he worked during WWII.
• Ticker tape depicting Alan Turing’s birth date (23 June 1912) in binary code. The concept of a machine fed by binary tape featured in the Turing’s 1936 paper.