Hut 4

Located initially in one of the original single-story wooden huts, the name "Hut 4" was retained when the section moved to a new brick building, Block A, in 1941.

Naval Ultra was handled differently from Army and Air Force Ultra because the Admiralty was an operational HQ and could give orders during a battle; while the Imperial General Staff (Army) and Air Staff would give directives to theatre commanders general orders say to "clear the enemy out of Africa" with discretion over how to do it. Verbatim translations of naval decodes were sent to the Naval Intelligence Division (NID) of the Admiralty's Operational Intelligence Centre (OIC) in London and nowhere else (except for some naval intelligence sent directly from Bletchley to Commanders-in-Chief in the Mediterranean).[2]

Hut 4 also decoded a manual system known as the "dockyard cipher". This sometimes carried messages that were also sent on an Enigma network. Feeding these back to Hut 8 provided excellent cribs for breaking the current naval Enigma key.

• M. M. G. Jennings (Margaret Allan), racing driver[3]
• J. W. B. Barns, later Professor of Egyptology at Oxford
• Sarah Baring, later Viscountess Astor
• Osla Benning, Prince Philip's first girlfriend
• Jocelyn Bostock from Lady Margaret Hall (LMH) Oxford, assistant to Hinsley [4]
• Alec Naylor Dakin
• Leonard R. Palmer, later Professor of Comparative Philology at Oxford.[5]
• Bernard Willson

Note: Frank Birch and Harry Hinsley were both associated with the naval section (Huts 4 & 8).

• Asa Briggs Secret Days: Code-breaking in Bletchley Park (2011, Frontline Books, London) ISBN 978-1-84832-615-6
• Peter Calvocoressi Top Secret Ultra (1980, Cassell Ltd, London) ISBN 0-304-30546-4