The plot was an original story by T. E. B. Clarke, a writer of both comedy and drama scripts for Ealing; his other screenplays for the studio include "Hue and Cry" (1947), "Against the Wind" (1948), "The Blue Lamp" (1950), "The Lavender Hill Mob" (1951) and "The Titfield Thunderbolt" (1953). Clarke was inspired by an incident during the Second World War, when the maternity ward of Ottawa Civic Hospital was temporarily declared extraterritorial by the Canadian government so that when the then-Princess Juliana of the Netherlands gave birth to Princess Margriet of the Netherlands, the baby was born on Dutch territory, and would not lose her right to the throne. The airlift of food supplies into the Burgundian enclave was influenced by the flights of food and supplies during the Berlin Blockade of June 1948 – May 1949. The music for the film was composed by Georges Auric, who had been involved in several other productions for Ealing Studios.