Among the English chessplayers in Bletchley Park were Hugh Alexander, Stuart Milner-Barry and Harry Golombek. All of them were part of the English National team at that time.
Milner-Barry later occupied a high post in English ministeries, Golombek worked as chess publisher and arbiter, while Alexander became director of the MI5 encryption department. This stopped him from playing any tournaments in the Eastern bloc and thus presumably robbed him of a chance to get the GM title.
See the article.