British playwright, poet, and man of letters whose verse plays express the contrast between traditional religious faith and the materialism and skepticism of modern times.

From an early interest in socialism, Duncan moved to the expression of Christian and Buddhist convictions in his literary work. He is best known for a number of plays that express in intense, poetic language his sense of the decline of moral values and the growth of skepticism in contemporary society. Among these plays are This Way to the Tomb (1945), Stratton (1949), Our Lady's Tumbler (1951), Don Juan (1953), The Death of Satan (1954), and The Catalyst (1958). His Collected Plays appeared in 1971. Duncan also wrote television plays, verse, short stories, novels, and many works of nonfiction, including three volumes of autobiography (All Men Are Islands, 1964; How to Make Enemies, 1968; and Obsessed, 1975), The Encyclopaedia of Ignorance, 2 vol. (1977), and A Memoir of Benjamin Britten (Britten, Benjamin) (1981). He wrote the libretto for the English composer Benjamin Britten's opera The Rape of Lucretia (1946), and he was a founder in 1955 of the English Stage Company. He served as poetry editor of The Townsman, a literary magazine he founded, from 1938 to 1946.