Before Bletchler Park

The Codebreakers of the First World War. Although much has been written about Bletchley Park and Second World War codebreaking, there has been comparatively little written about Room 40 and First World War espionage. Using hundreds of intercepted and decrypted German military, naval and diplomatic messages, bestselling author Paul Gannon reveals the fascinating story of British codebreaking operations. And by drawing on many newly discovered archival documents which challenge misleading stories about Room 40 and MI1(b), he reveals a sophisticated machine in operation.