Montgomery graduated from St John’s College, Oxford, in 1943, with a BA in modern languages, having for two years been its organist and choirmaster. From 1943 to 1945 he taught at Shrewsbury School. He first became established under his own name as a composer of vocal and choral music, including An Oxford Requiem (1951), but later turned to film work, writing the scores for many British comedies of the 1950s, most notably the Carry On series. He composed six scores for Carry On producer Peter Rogers including the original Carry On theme subsequently adapted for later films by Eric Rogers. Montgomery was responsible for both the screenplay and score of Raising the Wind (1961). Montgomery’s output of music and fiction all but ceased after the 1950s, but he continued to write reviews of crime novels for the Sunday Times. Alcoholism was a factor in his early death from a heart attack.

Under the pseudonym Edmund Crispin, Robert Bruce Montgomery wrote a series of mystery novels and short stories featuring the character Gervase Fen.