[5] Merivale made his acting debut at age 15, playing the small role of a newsboy in James Whale's The Invisible Man (1933).

[2] His stage career started when he was 21, as an understudy in a production of A Midsummer Night's Dream, where he first met Vivien Leigh.

[6] Merivale's career was put on hold while he served as a pilot with both the British and Canadian air forces during World War II.

[2] Although Merivale had the leading role in the Italian horror film Caltiki - il mostro immortale (1959), he tended to concentrate on theatre work, in such productions as Venus Observed, Anne of the Thousand Days, The Reluctant Debutante and The Last of Mrs.

[8][1][9] He was married to the US actress Jan Sterling from 1941 until 1948, and lived with Vivien Leigh from 1960 until her death in 1967, becoming her dedicated caretaker[10] in her final years.