His many notable screen roles include the High Sheriff of Nottingham in The Adventures of Robin Hood (1938), Mr. Collins in Pride and Prejudice (1940) and the wedding-rehearsal supervisor Mr. Tringle in Father of the Bride (1950).

[1] His budding acting career was interrupted by his military service in the Scottish regiment during the First World War, in which he was captured on the Western Front and held prisoner by the Germans for a brief time.

[2] In 1934, after receiving good reviews for his performance in The Private Life of Don Juan, Cooper moved to the United States.

During the 1940s, Cooper continued to appear in some of the more popular films of the decade, including Alfred Hitchcock's Rebecca (1940) with Joan Fontaine, Pride and Prejudice (1940) with Greer Garson, The Lady Eve (1941) and You Belong to Me (1941) with Barbara Stanwyck and Henry Fonda, This Above All (1942) with Joan Fontaine, Random Harvest (1942) with Greer Garson, Henry Hathaway's 13 Rue Madeleine (1947) with James Cagney and The Red Danube (1949) with Walter Pidgeon.

Towards the end of his career, Cooper focused on stage work and appeared in such productions as The Liar (1950), Much Ado About Nothing (1952), Escapade (1953), My Fair Lady (1956–62) and Hostile Witness (1966).