Remembered for his Hugo Award-nominated science fiction works The Ragged Astronauts (a 1987 novel) and "Light of Other Days" (a 1966 short story), he is also notable for his stories for numerous Irish sci-fi fanzines and for his two Best Fan Writer Hugo Awards.
He encountered his first science fiction short story, a work by AE van Vogt, when he was eleven years old and was deeply influenced by this early experience. He went on to study at the Belfast College of Technology and to subsequently join an Irish fan fiction writing group.
Apart from his career as a writer, he worked as a Belfast Telegraph science correspondent and an aircraft engineer and designer.
The son of a police officer, he grew up in Belfast, Northern Ireland with two younger brothers. During his first marriage, to Sadie Gourley, he had three children and lived temporarily in Canada. He later married an American woman named Nancy Tucker and lived in the United States and England.
He was born in the same year as fellow science fiction writer Gene Wolfe.