Made by the GPO Film Unit and sponsored by both the Empire Tea Marketing Board and the Ceylon Tea Board, Song of Ceylon is one of the most critically acclaimed products of the documentary film movement. It was hailed at the time of its release by author and film critic Graham Greene as a cinematic masterpiece, and received the award for best film at the International Film Festival in Brussels, 1935. The film is a sophisticated documentary, notable for its experimentation with sound. It features crucial input from Alberto Cavalcanti, who helped with the soundtrack, as well as composer Walter Leigh, who experimented in the studio to create a number of sound effects.