Clements attended Street Paul"s School and Street John"s College, Cambridge then worked with Nigel Playfair and afterwards spent a few years in Ben Greet"s Shakespearean Company.
He made his first stage appearance in 1930. Clements founded the Intimate Theatre at Palmers Green in 1935, which is a combined repertory and try-out theatre. He appeared in almost 200 plays, and presented a number of plays in the West End as actor-manager-producer.
He also started his film work in 1933.
Clements was the artistic director of the Chichester Festival Theatre from 1966 to 1973. In 1952 they both appeared in Clements" own play The Happy Marriage, an adaptation of Jean-Bernard Luc"s Le Complexe de Philemon.
Clements starred as Edward Moutlon Barrett in the musical Robert and Elizabeth, a successful adaptation of The Barretts of Wimpole Street. As a film actor John Clements played bit parts of increasing size for Alexander Korda"s London Films in the 1930s.
He made quite an impression opposite Robert Donat and Marlene Dietrich in Knight Without Armour as Poushkoff, an over-sensitive commissar who saves their lives during the Russian Revolution.
He came to further prominence when film director Victor Saville chose him to star opposite Ralph Richardson in. The two actors were reunited in the very successful The Four Feathers (1939). After this Clements" film career was somewhat intermittent although he made a series of British war films for Ealing Studios and British Aviation Pictures, such as, Ships with Wings (1942), and as Yugoslav guerrilla leader Milosh Petrovitch in Undercover (1943).
He had a cameo role (as Advocate General) in.
Clements was made a Commander of the British Empire (Commander of the Order of the British Empire) in 1956 and knighted in 1968. He died in Brighton, East Sussex in 1988.
Married Kay Hammond, August 21, 1946 (deceased 1980).