This was Michael Denison's last film until Shadowlands - Ein Geschenk des Augenblicks (1993), which was his final film overall, 33 years later.
Although John Ireland plays John Gregson's younger brother in this film, he was, in fact, five years Gregson's senior.
Final film of Joyce Marlow.
Based on the novel "Les Visages De L'Ombre" by Pierre Boileau and Thomas Narcejac, who also wrote "D'Entre Les Morts", the novel on which "Vertigo" was based.