That night train, gliding from London’s smoky tracks toward the silence of the North, carries not only letters but also the mechanical spirit of the era. The rhythmic clatter on the tracks blends with the feverish work of sleepless postal workers in the darkness of the night. Directed by Harry Watt and Basil Wright, this documentary captures the workday unfolding inside the train cars and the postal journey stretching toward Scotland with unadorned realism. The metallic sound of modernization stands side by side with the tranquility of the landscape.