Best known for his portrayals of upper-class military types, Donald Hewlett's father was Conservative MP for Manchester Exchange. He studied geography and meteorology at St. John's College, Cambridge. Early in World War II, he served at the Fleet Air Arm station of Kirkwall in the Orkneys, providing weather reports for Atlantic convoys. He was later assigned to the Royal Navy during North Atlantic action aboard the light cruisers Malaya and Galatea. He rose to the rank of lieutenant. He was subsequently posted to Singapore, in charge of Japanese POW's and as entertainments officer.He graduated from RADA with the Athene Seyler Prize for Comedy and his first professional stage appearance was in repertory at the Oxford Playhouse. Hewlett became most familiar to British television viewers for his regular role in the sitcom It Ain't Half Hot Mum (1974), a series which was very popular at the time but is never repeated now because it is considered very politically incorrect. Cult television fans also remember him as Hardiman in Docteur Who: The Claws of Axos: Episode One (1971), one of the many British officials who came up against Jon Pertwee's Doctor in the series.