Purser is a composer, musicologist, and music historian. He is also a poet and playwright. He has published three books of poetry, including The Counting Stick (1976) and Amoretti (1985). He was born in Glasgow of Irish parents in 1942. He was educated at Lathallan School and Fettes College, and in 1963 studied Composition, Singing and Violoncello at the Royal Scottish Academy of Music and Drama. In 1992 his book Scotland's Music  won him the McVitie Scottish Writer of the Year Prize. An expanded edition of Scotland's Music was published by Mainstream in 2007 to accompany his second eponymous radio series for BBC Scotland. Of his six radio plays commissioned by the BBC, Carver  won a Giles Cooper Award and was published by Methuen. He lives on the Island of Skye.