The GPO Film Unit was a subdivision of the UK General Post Office. The unit was established in 1933, taking on responsibilities of the Empire Marketing Board Film Unit. Headed by John Grierson, it was set up to produce sponsored documentary films mainly related to the activities of the GPO.
Among the films it produced were Harry Watt's and Basil Wright's Night Mail (1936), featuring music by Benjamin Britten and poetry by W. H. Auden, which is the best known. Directors who worked for the unit included Humphrey Jennings, Alberto Cavalcanti, Paul Rotha, Stuart Legg, Harry Watt, Basil Wright and a young Norman McLaren.