In 1959 he made his West End debut in The Long and the Short and the Tall, and played the title role in Hamlet in the National Theatre's first production in 1963.

He attended the Royal Academy of Dramatic Art and began working in the theatre, gaining recognition as a Shakespearean actor at the Bristol Old Vic and with the English Stage Company. Peter Seamus O'Toole (2 August 1932 – 14 December 2013) was a British stage and film actor. As his character was part of the pipe band that Vesper machine gunned with her bagpipe Weapon, he may have died within the film. Peter Seamus O'Toole was a highly respected British/Irish actor who briefly appeared as himself in the 1967 Spy spoof Casino Royale'.