The Ipcress File was the first spy novel by Len Deighton, published in 1962.
The Ipcress File was a downbeat alternative to the James Bond movies, which were being made at the same time. Three members of the production team -- the producer Harry Saltzman, film editor Peter Hunt and the composer John Barry -- also worked on the Bond movies.
The plot involves mind control: the acronym IPCRESS stands for "Induction of Psycho-neuroses by Conditioned Reflex with streSS".
The soundtrack music by John Barry is excellent, and complements the action on screen superbly.
See also: MKULTRA