According to various books on Hammer films, this film went over schedule and some key scenes were never filmed. Rank called it Hammer's best film in years.
The reputed "Billy Smart's Circus" provided a number of the circus performers, extras, and background artists.
Domini Blythe's first feature film and only on-screen nude scenes, though before she started acting, she performed totally nude in the play Oh! Calcutta.
Laurence Payne was an 11th hour casting choice replacing Anton Rodgers, who dropped out because of illness.