This was the last film to be directed by Sir Carol Reed.

The play premiered at the Globe Theatre, London, in 1962, and starred Richard Pearson as Charles, Maggie Smith as Belinda and Kenneth Williams as Julian.

In January 1964 Variety noted that Ross Hunter bought the screen rights to Peter Shaffer's play and hired Mike Nichols to direct, and in February 1965 Daily Variety announced that Julie Andrews was to star. In December 1965 The Hollywood Reporter wrote that the production would be delayed because Nichols was tied up editing Who's Afraid of Virginia Woolf? (1966). In June 1967 Nichols and Andrews dropped out of the project, and Hunter made a deal with Richard Burton and Elizabeth Taylor to star in the picture. Their contract granted them the right to approve the director and third lead; at the time Paul Scofield and Dirk Bogarde were being considered for the third lead. Burton and Taylor withdrew from the project after not being able to agree upon a suitable director.

In 1969, it was widely reported that the film would be made with Rex Harrison playing the husband, Marcello Mastroianni playing the detective and Faye Dunaway (with whom Mastroianni was having a rather public romance at the time) playing the wife.

At the start of the film, a bus pulls up to the front of the detective agency. One of the advertisements on the bus is for the movie See No Evil (1971) (known as Blind Terror in the UK) starring Mia Farrow.

In August 1968 Daily Variety news said that Katharine Ross was going to star in the film.