Donald Hewlett's family background is marked by his father's notable career as a Conservative MP for Manchester Exchange. Hewlett himself pursued higher education, studying geography and meteorology at St. John's College, Cambridge. During the early stages of World War II, he played a crucial role at the Fleet Air Arm station in Kirkwall, Orkneys, providing vital weather reports for Atlantic convoys. His exceptional service earned him a promotion to the Royal Navy, where he served on board the light cruisers Malaya and Galatea, rising to the rank of lieutenant.
Following his military stint, Hewlett was posted to Singapore, where he was responsible for overseeing Japanese POWs and entertaining them in his capacity as an officer. After the war, he continued his education, graduating from the Royal Academy of Dramatic Art (RADA) and receiving the Athene Seyler Prize for Comedy.
Hewlett's professional stage debut took place in repertory at the Oxford Playhouse, marking the beginning of his illustrious career. He is perhaps most well-known for his recurring role in the popular British sitcom It Ain't Half Hot Mum (1974),which, although extremely popular during its initial run, is no longer broadcast due to its perceived political incorrectness.
In addition to his work in It Ain't Half Hot Mum, Hewlett is also remembered by cult television enthusiasts for his portrayal of Hardiman in The Claws of Axos: Episode One (1971),a role that showcased his ability to convincingly play British officials who often found themselves at odds with the iconic Doctor, played by Jon Pertwee.