His first play, Dante Kaputt, was staged at the Phoenix Theatre, Leicester, in 1966. Subsequent plays were premiered at the Traverse Theatre, Edinburgh and the Stables Theatre in Manchester, where Harrison was Resident Playwright during 1969 and '70. His drama output for radio and television includes numerous award-winning plays, among them the WorldPlay award in 2005 for the best play from an English-language broadcaster. This play, Hitler in Therapy, was Harrison's 100th drama to be recorded in a UK studio.
17 hours of Harrison's teleplays have been seen on Masterpiece Theatre, including the miniseries Freud,.
He is the author of 16 novels, most notably Richard's Feet, published by Holt in the U.S. and by Heinemann in Britain, winner of the Encore Award from the UK Society of Authors. Harrison has received numerous grants from the UK Arts Council, and his prizes include Sony awards, the Giles Cooper Award, the Prix Marulic, the UK Writer's Guild Award for Best Play, the Prix Italia Silver Award and the Best Play award from the Berlin Society for the Arts, as well as two nominations (2005 and 2007) for the Pushcart Prize for Journalism. His work has been translated into thirteen languages. His output includes published translations from French, Italian, German and Spanish authors, and performed translations from the works of Pirandello, Goldoni, Feydeau and the late Gert Hofmann; most recently he published 20 Poems from the Arabic of Firas Sulaiman, in Banipal, the UK magazine of contemporary Arabic writing. Since 2005 he has contributed a monthly essay on linguistic trends in The Vocabula Review. He has also been a book reviewer for numerous newspapers including the San Francisco Chronicle, the Chicago Tribune, and the New York Times.