The “cult of Alan Turing” has been taken to absurd extremes, the codebreaker’s nephew has claimed as he argued that it had overshadowed Bletchley Park’s debt to Polish cryptographers.

Sir Dermot Turing said that his uncle’s achievements in cracking German communications encrypted on the Enigma machines were based on work by a group of Polish mathematicians.

Marian Rejewski was among the Poles who had been studying Enigma messages JANINA SYLWESTRZAK

Sir Dermot, a solicitor who has written a biography of his uncle and who is a trustee at Bletchley Park, was speaking before the release next month of his book X, Y & Z, which explores the attempts of Britain, France and Poland to master the Enigma machines, deemed crucial to the defeat of Nazi Germany.

He has pieced together the role of Poles who had been studying