Thorne began his musical career as a pianist with the big bands of England during the 1940s, playing at night clubs and the dance halls.

When Henry Mancini was scoring Blake Edwards's 1968 film The Party with Peter Sellers, Thorne composed the soundtrack to Inspector Clouseau.

He also composed the music scores for How I Won the War (1967), The Monkees movie Head (1968), The Magic Christian (1969) and The Ritz (1976).

His television work included the theme to the 1964 BBC series R3, and he also scored incidental music for The Persuaders!

[2] As a conductor, orchestral arranger and music coordinator, Thorne also achieved notoriety for his contributions to the English version of Franco Zeffirelli's film Brother Sun, Sister Moon in 1973.