The original Broadway production of "Inadmissible Evidence" by John Osborne opened at the Belasco Theater on November 29, 1965, ran for one hundred sixty-seven performances and was nominated for the 1966 Tony Award for the Best Play. Peter Sallis re-created his stage role for this movie, as did Nicol Williamson, who was nominated for the 1966 Tony Award for Actor in a Drama. Author John Osborne also wrote the screenplay.
Dame Eileen Atkins shunned movies for several years because of her uncomfortable time working on this movie.