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.
Alan Turing will be the face on the £50
Bank of ENGLAND will issue a new £50 note in 2021. It will be the first £50 note printed on polymer.
Design features on the note
The new £50 note, our first £50 printed on polymer, 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.

from Bank of ENGLAND