The most well-known and widely distributed of the experimental documentaries produced by the General Post Office Film Unit in the 1930s, Night Mail is, like Coal Face, a collaboration with composer Benjamin Britten and the poet W. H. Auden. Like many montage films of the period, the emphasis is on process, here the different phases of mail delivery. Recurring visual and auditory motifs link the different strata, environments, and regions of Britain in striking and sometimes surprising ways.