After studying at RADA, Glaister made his West End debut in 1939. With the outbreak of war, he joined the Royal Air Force, commissioned as Pilot Officer on 8 September 1939 and initially flying a Blenheim bomber. He later served as a photo reconnaissance pilot in 208 Squadron RAF in the Western Desert, initially flying Westland Lysanders. It was during these latter duties that he was awarded the Distinguished Flying Cross on 6 October 1942, for a hazardous reconnaissance flight in an unarmed Hurricane at extremely low level across the Italian front line. He rose to the rank of Squadron Leader and retired from the RAF on 5 August 1952 (for medical reasons).[5] Glaister later drew on his RAF experiences when, in 1963, he produced Moonstrike, a drama about resistance agents in occupied Europe during the Second World War. From 1962, he worked on the popular Dr Finlay's Casebook.[1] His 1968 production The Expert is based on the work of his uncle, forensic scientist Prof John GlaisterFRSE.[6]
Glaister's success ended with the 1991 series Trainer,[1] which was moved from prime time to a weeknight slot because of its perceived failure. However, it sold well overseas.[7]
Glaister was married three times and had three daughters, two from his final marriage, to Joan.[1]