John Grierson’s documentary unit of the British General Post Office produced gems such as Night Mail. This film brings to life the nightly run of the mail train, the Postal Special, from London to Glasgow, Edinburgh, and Aberdeen. Few subjects have been more splendidly suited to cinematic ingenuity, as the film delightfully documents the complex procedures and cooperative efforts of professionals who take pride in a job well done, matched by machines that readily snatch mail pouches at full speed. The film crew itself was a triumph of collaboration in the “creative treatment of actuality,” with Alberto Cavalcanti, W.H. Auden, and Benjamin Britten brilliantly bringing sound to the documentary.