Born in Alyth, Sharp was adopted and raised in Greenock. Leaving school at 14 Sharp did a variety of jobs before moving to London with the intention of writing.
In 1965, his screenplay 'A Knight in Tarnished Armour' was broadcast by the BBC. He also published his first novel 'A Green Tree in Gedd'e', which won the Scottish Arts Council Award in 1967, the same year he published 'The Wind Shifts'.
Sharp emigrated to the USA where he found critical and popular success writing film screenplays, also moving into television in the 1980s and 1990s. His feature film projects included The Osterman Weekend (1982), Rob Roy (1995) and Dean Spanley (2008).
Sharp married four times and had a total of six children