Notable for his roles as Gregory and The Bloody Baron in the respective films Monty Python's Life of Brian (1979) and Harry Potter and the Sorcerer's Stone (2001), he is also known for his stage work, as well as for his television appearances on Doctor Who, Ivanhoe, Rutland Weekend Television, and Upstairs, Downstairs.
Early in his career, he played the role of Tom in the 1952 film Broken Barrier.
He portrayed Macduff in the 1971, Roman Polanski-directed film version of the Shakespearean tragedy Macbeth.
He was born in Wanganui, New Zealand, to Harold and Amy Bayler.
He appeared in director Terry Gilliam's 1980s features Brazil and Time Bandits.