Many of his plays were later adapted for both stage and television. "Unman, Wittering and Zigo", "Seek Her Out", in which a woman (played by Toby Robins) witnesses an assassination on the London Underground and becomes the next would-be victim of the perpetrators; and "The Long House" were parts of an unrelated trilogy of plays by Cooper broadcast on BBC2's "Theatre 625" during the summer of 1965. He also wrote "The Other Man" a television drama starring Michael Caine, Siân Phillips and John Thaw and first broadcast on ITV in 1964. "Everything In The Garden" was first performed by the Royal Shakespeare Company in 1962 at the Arts Theatre, London; in 1967, an American adaptation by Edward Albee, was first performed in 1967 at the Plymouth Theatre, New York City, and dedicated to Cooper's memory.