Lawson is best known for his roles as Wedge Antilles in the original Star Wars trilogy, and as Gordon Urquhart in the film Local Hero. He has also gained some fame for being the uncle of actor Ewan McGregor. He was born in Perthshire, Scotland.
Lawson began his career with a small role in a 1969 stage production of The Metamorphosis in London's West End, and has since starred in television dramas such as Rock Follies (1976) and Dead Head (1986).
In 2005, he played the leading role of John Jarndyce in the critically-acclaimed BBC adaptation of Charles Dickens' Bleak House, receiving an Emmy nomination for his sympathetic supporting performance.
In 2007 he played the role of Tom Jackman's (James Nesbitt) oldest friend Peter Syme in the BBC One drama serial Jekyll, a modern version of The Strange Case of Dr Jekyll and Mr Hyde.