Extract relating to military intelligence work:
He won a scholarship for classics to New College, Oxford in 1939 and took the courses for Honour Moderations from 1940 to 1941 (during the Battle of Britain), achieving a First Class degree. ...
From 1942 to 1945 he served in the RAF. In 1942 the War Office came to realise that knowledge of foreign languages was an essential part of the war effort, and that, in particular, there was complete ignorance of Japanese. So Bobby was sent to a rather traditional short course of Japanese, was then given a commission and sent to the School of Oriental and African Studies in London to teach Japanese to service personnel, under the formidable J. R. Firth. According to what may well be a somewhat apocryphal story, the War Office discovered that the Japanese Air Force was able to send all their operation messages in clear, because no-one understood Japanese (and the Americans had detained all their citizens of Japanese origin). So they approached a Department of Japanese for help, only to be told that a course in Japanese would take four years! By some flash of inspiration, they then approached Firth, who realised that all that was needed was the ability to recognise a very small section of the spoken language (what he called a ‘restricted language’) and that this could be taught in a matter of months. There can be no doubt that Bobby’s experience in teaching Japanese (with the emphasis on the spoken language and this notion of a restricted language) under Firth was quite the most influential on his later work in Linguistics.
(See: List of humanities scholars who worked in military intelligence in the Second World War)