Innovative filmmaking might not be the first thing you think of when you hear the words “post office,” but Britain's General Post Office Film Unit, founded in 1933, became internationally renowned as a center for creative, exciting films. Author J. B. Priestley recalled: “If you wanted to see what camera and sound could really do, you had to see some little film sponsored by the Post Office.” This program of eight new prints from the BFI National Archive showcases the GPO Film Unit's sheer range, from quintessential documentary (Night Mail) to avant-garde animation (Trade Tattoo) and even musical comedy (The Fairy of the Phone). Made by such varied talents as John Grierson, Alberto Cavalcanti, Len Lye, Norman McLaren, and Lotte Reiniger, the films bring alive a revolution in mass communications as epoch-changing then as the Internet is now.