Because Charlotte Rampling's voice had recorded badly on the soundtrack, all her dialog had to be dubbed.
This film has clear links with two earlier comedies involving John Warren and Len Heath as writers. The name "Jelly Knight", used for the character of a small-time crook, is common to both this film, and to Two Way Stretch (1960) where the character is played by David Lodge. The character of "Anxious O'Toole", an Irish gang boss given to anxiety and played here by Victor Maddern, has clear links to The Wrong Arm of the Law (1963), where Bernard Cribbins plays an Irish gang boss given to nervousness and called "Nervous O'Toole".
Apparently Dirk Bogarde turned it down due to the casting of fellow actor Alfred Marks. Marks was not cast in the end.
The headstone for "The Duke" gives his full name as Randolph Berkeley-Greene. The inscription, appropriate for a thief, is "He took things as he found them".