Mathematician Alan Turing on the new £50 note Credit: Bank of England The final bank note to switch from paper to plastic will soon be in circulation, as the new £50 note featuring mathematician, code-breaker and computer scientist Alan Turing launches this summer. It will replace the note featuring steam engine pioneers James Watt and Matthew Boulton, who first appeared on the note in 2011. The launch of the new £50 note follows the successful introduction of a polymer £5 note in 2016 featuring Sir Winston Churchill, £10 note featuring Jane Austen in 2017, and £20 last year with painter JMW Turner. Why is Alan Turing on the new note?