At 15, he joined Glasgow's Youth Theatre[2] after he visited one night and met Robert Buchanan, a fellow fan of Canadian progressive rock group Rush.
[3] As a result, he starred in a number of films by director Bill Forsyth, perhaps the most notable of which is 1981's Gregory's Girl, shot when he was 19 years old.
He appeared in the 1982 Scottish squad's World Cup song "We Have a Dream", a number 5 hit in the UK, which was written and performed by B.
[4] Sinclair played Frank McClusky, a leading character, in the 1990 John Byrne TV serial Your Cheatin' Heart.
He played one of the main characters in the Tesco TV adverts in the late 1990s and early 2000s alongside Prunella Scales and Jane Horrocks.
He most recently appeared in the London's West End in The Producers playing the part of Leo Bloom alongside Fred Applegate.