Following his elder brother Jock, he emigrated to New Zealand when he was sixteen, working in sheep farming and lumberjacking, but only stayed for five years before auditioning to study at RADA, after begging his father to let him return to try to become an actor.

[7] He also had roles in Fire Crackers, The Buccaneers, Danger Man, Love Story, Rooms, Angel Pavement, Follyfoot, Telford's Change, When The Boat Comes In, The Sweeney, Dick Barton: Special Agent, The Seventh Juror, The Flockton Flyer, Headmaster, Thicker than Water (an instalment of the anthology series Play for Today), The Night People, The Omega Factor, The Greenhill Pals and The Pickwick Papers.

Fifty-two episodes were made by Granada TV and the series proved to be very popular and often drew a weekly audience of over 22 million viewers, sometimes knocking Coronation Street off the top spot.

Colin Douglas's last role was as troubled Labour Party veteran Frank Twist in Alan Bleasdale's TV series GBH.

[12] Their children are named Timothy, Amanda (killed, aged 20, in a traffic accident whilst at the University of Kent, Canterbury), Angus, Blaise and Piers.