Beesly, Patrick. Very Special Intelligence: The Story of the Admiralty’s Operational Intelligence Centre 1939-1945. Augmented new edition. London: Chatham, 2006 (1977). ISBN 978-1861762771 .
How Britain pioneered all-source fusion: uniting & mapping intelligence from decryption, signals, agents, local resistance, in a single “war room” frame – to win the naval struggle of WWII. I give ****/5.
(Webfront photo caption & credit here.)