He began working "in the round" in 1966, in weekly and fortnightly repertory theatres across the United Kingdom, Canada and Zimbabwe.
Harris has appeared in 50 television comedies and dramas and has played opposite Peter Cushing in Sherlock Holmes, Jack Warner in Dixon of Dock Green, Dennis Waterman in The Sweeney, Judi Dench in As Time Goes By, Jasper Carrot and Robert Powell in The Detectives, John Thaw in Mirch, James Bolam in Second Thoughts, Tom Conti in Old Boy Network, Adam Faith in Love Hurts, David Jason in Diamond Geezer, Warren Clarke in The Case of the Frightened Lady, Anthony Andrews in Ivanhoe, Eric Sykes in If You Go Down in the Woods Today, Michael Kitchen in Home Run, Larry Lamb in Fool's Gold and Bill Paterson in The Interrogation of John.
Other television appearances occurred in Z-Cars, Softly, Softly, Bergerac, Blake's 7,[1] Casualty, Coronation Street, EastEnders, Shoestring, London's Burning, Drop the Dead Donkey, Grange Hill, Heartbeat, Howards' Way, Silent Witness, A Touch of Frost, and five episodes of The Bill.
His voice work includes dramas on CBC Radio, the part of Vila in the initial audio recordings of Blake's 7.
He played opposite Derek Jacobi in "The Martian Chronicles" and has a five-page death scene in the audio version of Dan Dare.