Began his career writing intertitles for silent films, graduating to screenplays in the 1930s before eventually turning to directing. Working often with Frank Launder, Gilliat made a series of outstanding British comedies and suspense pictures from the mid-30s into the 1960s; among the team's screenwriting credits are "The Lady Vanishes" (1938) and "Night Train to Munich" (1940). Launder and Gilliat became known for thrillers with a comic element, such as "I See a Dark Stranger" (1946), "Green For Danger" (1946) and "State Secret" (1950). "The Belles of St. Trinian's" (1954) is one of their best-known outright comedies. Brother of producer Leslie Gilliat.