jcrt recommends 'Voices of the Code Breakers' by Michael Paterson and 'Colossus Bletchley Park's Greatest Secret' by Paul Gannon.

However, although Gannon's book is excellent, it won't help with Enigma, since Colossus was only used to solve an even more complex cipher machine, the Lorenz SZ 40/42 (codenamed Tunny by the British) and not Enigma.

Parts of 'Voices of the Code Breakers' on Enigma (and Colossus) are unreliable. Michael Paterson quotes chunks of Winterbotham's 'The Ultra Secret' without warning that they are very undependable (eg Winterbotham's account of how the Poles solved Enigma before the war, which is nonsense, since he claims that the Poles stole a machine from a German factory).

Dr Louis Tordella, a deputy director of the US National Security Agency described Winterbotham's book as "inaccurate in detail, and although it resembles the truth in outline, much of it is purely imaginary." No one will realise that by reading Paterson’s book.

RE