This was the second of two attempts by the British branch of M-G-M to turn Spike Milligan into a film star, after the previous year's Invasion Quartet (1961); but Milligan was not happy with it and once referred to it as "the serious version of that Jacques Tati film about a postman" (meaning Jour de Fête (1949), a film he greatly admired).
To coincide with the film's release, Parlophone released a promotional record. The song is "Postman's Knock", the song over the opening credits. Another promotional record, "Wormwood Scrub's Tango", was also released.
This film failed at the box office, resulting in a loss to MGM of $31,000 according to studio records.
Harold offers to pay Jean £3 a week for lodging and breakfast. That equals about $8.43 at the time, which equates to around $73 in 2020.
The thick book Harold had rigged to wake him up by hitting him in the head with it when the alarm clock rang is "Le Trille du Diable" by Suzanne Roland-Manuel, 1946 edition, 667 pages.