The success of this movie, in spite of its controversial themes, encouraged Janet Green to write "Victim", and Basil Dearden to direct it.

Dirk Bogarde was asked to play Learoyd.

Feature film debut of Fenella Fielding.

The ripped photo used as a clue appears in two versions from the first time it's discovered. The first version shows Sapphire laughing as she dances, with her mouth open. The second shows her smiling broadly with her jaw closed. It's quite an odd, unnecessary blunder in a police procedural.

Opening credits: All characters and events in this film are fictitious.Any similarity to actual events or persons, living or dead, is purely coincidental.