He worked alongside Laurence Olivier as a founding director of the National Theatre from its time at the Old Vic in 1963. In 1962, he directed Vanessa Redgrave and Eric Porter in Cymbeline for the Royal Shakespeare Company.
He was the artistic director of the Royal Court Theatre between 1965 and 1972, where he directed premieres of plays by writers including David Hare, John Arden, Edward Bond and Arnold Wesker, as well as introducing many of Bertolt Brecht's works to British audiences.
William Gaskill is an associate member of the Royal Academy of Dramatic Art.
Gaskill, W. (1990), A Sense of Direction, Limelight Editions, ISBN 0-87910-134-2