This is a history of the Operational Intelligence Centre of the RN's Naval Intelligence Division in WW2, and its satellite the Submarine Tracking Room. The author was an early recruit to the OIC and brings this story to us as an informed insider rather than a speculative journalist. In compiling this very readable account in 1977 he was able to enjoy the cooperation of many 'Old Boys' of NID so ensuring a true bill, enabling him to navigate the often patchy or even non-existent official records.
The OIC was created by the genius of the WW2 NID, Admiral John Godfrey, veteran of WW1's Room 40, who saw the need to correlate all sources of naval intelligence including code breaking ('Special Intelligence' or, demotically, 'Ultra'), traffic analysis, Direction Finding, agents, aerial photo reconnaissance, PoW interrogation and so forth. Many of these took time to get up to speed and indeed for Authority to agree to their being sensibly resourced and prioritised. Ultra is seen as often sporadic, stale, broken or intermittent and this joined up story shows how the other resources were essential to the total picture. Nevertheless the OIC, ill-housed, under-staffed and overworked made a major contribution to the Atlantic War, profiting from two other genii, (eventual) Vice Admiral Sir Norman Denning and Rodger Winn and an amazingly talented and very heterogeneous collection of recruits. Winn became, most unusually, a Captain in the RNVR having proved himself uncannily accurate in predicting Doenitz. All came under a First Sea Lord, Pound, who clearly lacked the intelligence fully to understand Intelligence.
Beyond the daily grind against the U-boats there are insider narratives of the Bismarck Chase, the 'scattering' of PQ17 and the sinking of the Scharnhorst. The story takes us right to the end of the war as the OIC tries to predict the numbers and deployment of much advanced U-boats, they mercifully overtaken by Germany's collapse.
We have here a very welcome 2015 Seaforth reprint of the 2000 edition that included an introduction by WJR Gardner (author of 'Decoding History: The Battle of the Atlantic and Ultra'), and an 'Afterword' by Ralph Erskine, co-author of 'The Bletchley Park Codebreakers', covering the rock-strewn history of British, German and US WWW2 cryptanalysis, and explaining the practical difficulties of improving our own coding methods. There is a rich bibliography.