Composer, academic and first Chairman of Scottish Opera. Born in Brechin, Orr was educated at Loretto School in Musselburgh and the Royal College of Music. He was appointed Organ Scholar of Pembroke College, Cambridge (1929) and thereafter continued his studies in Italy and France. He spent three years as a music teacher at Sidcot School (Somerset, England) and was then appointed an assistant lecturer at the University of Leeds. He moved to Cambridge, becoming Organist and Director of Music at St John's College (1938-51). After service as a photographic intelligence officer during World War II, he was appointed a University Lecturer at Cambridge and began to compose seriously. He also held a Professorship at the Royal College of Music. He accepted Chair in Music at the University of Glasgow (1956) and returned to a Chair in a new Faculty of Music at Cambridge in 1965.
Along with Sir Alexander Gibson (1926-95), Orr was one of a group who founded Scottish Opera in 1962, and he served as its first Chairman until 1976. He was also a Director of Welsh National Opera (1977-82).
His works include a Symphony in One Movement, first performed by Alexander Gibson at the Proms in 1966; two further symphonies (1971 and 1978); three operas, Full Circle (1967), commissioned by Scottish Television for Scottish Opera and based on the words of poet Sydney Goodsir Smith (1915-75), Hermiston, performed at the 1975 Edinburgh Festival, and On the Razzle, commissioned by the Royal Scottish Academy of Music and Drama in 1988; a song cycle, From the Book of Philip Sparrow, premiered in Glasgow in 1969 by mezzo-soprano Janet Baker, and The Sinfonietta Helvetica (1991) in honour of the 700th anniversary of the founding of the Swiss Confederation. He has also written notable chamber and church music.
Orr was awarded a CBE in 1972 and honorary degrees from Universities of Glasgow and Dundee. His autobiography is entitled Musical Chairs (1998).