Inaugurating his film career as an assistant cameraman, Manchester-born Bernard Knowles graduated to full lighting cameraman (the British equivalent of "cinematographer") in 1928. During the 1930s Knowles was most closely associated with director Alfred Hitchcock, lensing such thrillers as The 39 Steps (1935) and Jamaica Inn (1939). A director from 1945, Knowles at first specialized in costumers, notably Jassy (1946) and The Magic Bow (1947). In 1949, he wrote and directed the delightful sci-fi comedy The Perfect Woman (1949), after which his films became increasingly routine. Bernard Knowles retired from the big screen in 1968, though he remained active in British television.