One of the set of 129 photographs of the Government Code and Cypher School at Bletchley Park. This one shows rows of cabinets probably containing 5in x 9in index cards.
Good, Jack; Michie, Donald; Timms, Geoffrey (1945), General Report on Tunny: With Emphasis on Statistical Methods, UK Public Record Office HW 25/4 and HW 25/5
2014-03-30 17:57:32
UK Government public domain