Malcolm Arnold
Arnold wrote music for 132 films.  The most famous is The Bridge on the River Kwai (1957) for which he won an Oscar.  He was the first British composer ever to have won this award. This movie includes the famous Colonel Bogey March.  This march had been written many years earlier by Kenneth J. Alford, but Arnold composed a countermelody to it.  His original music for the movie includes the famous River Kwai March (this is not the same as the Colonel Bogey March).   Other movies for which he wrote music include The Belles of St Trinian's (1954), The Inn of the Sixth Happiness (1958) and Whistle Down the Wind (1961).