New British £50 note with Second World War codebreaker Alan Turing enters circulation

Computer scientist finally honoured for service to country

A new £50 banknote featuring the mathematician and computer scientist Alan Turing enters circulation in Britain on Wednesday, three months after the Bank of England first unveiled the design.

Turing is best known in Britain for designing machines to decrypt coded messages during the Second World War.

Before the war his work laid the theoretical foundation for modern computer science. Later he made discoveries in developmental biology.

"Placing him on this new banknote is a recognition of his contributions to our society, and a celebration of his remarkable life," Bank of England Governor Andrew Bailey said.

Turing, who was gay, lived at a time when sex between men was illegal in Britain.

He was given a criminal conviction in 1952, lost his security clearance and died of cyanide poisoning less than two years later in what coroners ruled was suicide.

Britain's government issued a posthumous pardon in 2013 and Mr Bailey said Turing had been treated appallingly while alive.

Britain's GCHQ spy agency, a successor to the branch for whom Turing worked in the Second World War Two, unveiled an artwork in his honour on Wednesday.

The new £50 banknote completes the BoE's transition from paper to polymer. Paper £50 banknotes will circulate alongside the new polymer ones until the end of September 2022.

Fifty-pound notes account for 357 million of the more than 4.5 billion Bank of England notes in circulation. Lower-denomination notes are more popular for day-to-day transactions.