During World War II, the Government Code and Cipher School, a secret organisation and forerunner of the modern day Government Communications Headquarters in the UK, read millions of encrypted German operational and strategic communications. This organisation employed around 10,000 people and was based at a country estate called Bletchley Park, about 50 miles north of London. The general view by historians is that this work helped bring the war to an end and saved countless lives.


The Official Secrets Act and the passing of time have prevented the Bletchley Park story from being told by many of its key participants. Here at last is a book which allows some of them to speak for the first time. The author has been able to draw on Gordon Welchman’s personal correspondence with wartime colleagues which lay undisturbed in his son’s loft for many years. Welchman was one of Bletchley Park’s most important figures and author of the seminal book, The Hut Six Story. It was Welchman who came up with the plan for a production line approach to the decryption of Germany’s secret communications. His book was the first to reveal not only how they did it, but on an industrial scale.


This book draws extensively on Welchman’s personal diaries and papers to reveal his thoughts on a number of Bletchley Park personalities including Alistair Denniston, Edward Travis, Dilly Knox and Alan Turing.  His working relationship with Turing is particularly intriguing as is the story of the Bombe machine and Welchman’s contribution to its ultimate success. It tells the story of the last two years of Welchman’ s life, spent trying to finally set the record straight about the wartime contributions of the Polish codebreakers as well as Denniston and Knox.


Included is detail of Welchman’s post-war career in the fledgling American computing industry and of the key developments there which paralleled those taking place in Britain.


Revealed for the first time is the story behind Welchman’s book and his subsequent treatment by both GCHQ and its American counterpart, the NSA. A recently declassified government document finally provides some of the rationale behind their actions.

Image: Cover of the Welchman biography.