Seabrook was born in
Northampton on 14 November 1939. He was educated at
Northampton Grammar School and
Gonville and Caius College, Cambridge, graduating with a degree in Modern and Medieval Languages in 1960. He worked as a teacher and as a social worker, and began writing for the journal
New Society in 1963. In addition to contributing articles to newspapers and magazines, Seabrook has also written numerous books and plays for television, radio and theatre, including several collaborations with his old schoolfriend Michael O'Neill. Seabrook died at a care home in London, on 30 November 2024, at the age of 85. ==Written works (partial list)==