Ellis is the author of The Beginning of the End: The Crippling Disadvantage of a Happy Irish Childhood, the story of his early life in Belfast, Durham, Cork, and Brussels, and his uneasy relationship with his cousin, Ronnie Bunting. He also wrote The Oxbridge Conspiracy:How the Ancient Universities Have Kept Their Stranglehold on the Establishment (ISBN 0718137485/ISBN 9780718137489), a study of elitism in higher education in England.

He has lived in New York since 2001. His wife Louisa is a graphic designer and painter. Their son, Jamie Ellis, is a musician.

Walter Ellis, formerly a journalist and foreign correspondent for several British and Irish newspapers, is moving into the field of fiction. His thriller, Waiting for Wallenberg, is awaiting publication.