The original poster art for the film was an eerie black and white family portrait of "The Family," dressed in traditional English attire (six form uniforms for Girly and Sonny, a maid's outfit for Nanny, and a World War II era dress for Mumsy). Though this iconography would have struck a chord with British viewers, it was deemed that US audiences wouldn't understand the image. For the US release, the distributor commissioned a poster of an anonymous girl standing in for Vanessa Howard, wearing a cutoff skirt and clutching a doll in one hand and a bloody axe in the other.
Based on the play "Happy Family." Director Freddie Francis specifically asked screenwriter Brian Comport to write a story built around Oakley Court, the house where the movie was filmed. Comport and Francis found "Happy Family" to be a good jumping-off point for the story, but neither one actually liked the play. The movie only retains the four principal characters' names and the idea that they bring men home to participate in a role-playing game.
Born out of cinematographer and latterly director Freddie Francis' desire to make a film over which he had complete creative control as opposed to being a director for hire.