The capture of a working Enigma coding machine from the sinking U110 in May 1941, the pursuit of the battleship Bismarck later the same month, and the reason why British naval cryptographers won stole a march - when their own naval code had been cracked by the other side.

David Boyle is a co-director of the New Weather Institute, and the author of a number of books about economics, business and the future, as well as history, including 'Blondel’s Song' and 'Toward the Setting Sun', about the discovery of America. He has written a series of successful titles, including 'Unseen, Unheard: Submarine E14' and the Dardanelles and the bestselling 'Alan Turing: Unlocking the Enigma'.