Originally trained as a doctor, Orr gave up medicine and switched to music, studying composition with Benjamin Frankel and conducting with Aylmer Buesst. Best known for his personal application of serial technique and for several virtuoso instrumental fantasies on well-known operatic themes, he was also active for a time in the film industry as well as being an energetic and influential teacher. His music includes works in all genres, including songs, chamber music, works for brass and wind band, orchestral music, opera and music theatre as well as film scores. In 1990 he gave up regular teaching to devote more time to composition, and lived in the Wye Valley until his death. He was not related to the composer Robin Orr.
Works for wind band; Tournament, Trombone Concerto, Narration, A Caledonian Suite, Piano Trios 1, 2, and 3 (recorded on Marco Polo in 1996)
- Grip of the Strangler (1958);
- Fiend Without a Face (1958);
- Corridors of Blood (1958);
- The Flying Doctor' (1959) [TV Series (additional music)];
- First Man Into Space (1959);
- Suddenly, Last Summer (1959);
- Doctor Blood's Coffin (1961);
- Snake Woman (1961) (aka: Terror of the Snake Woman);
- The Eyes of Annie Jones (1964);
- Walk a Tightrope (1965).
Other musical works
Some of his stock music was used in several "Doctor Who" serials.
List of works: 
Another page on Orr: