Detective Inspector Gregory
Leopold Dryden
Joan Dryden
Rodney Fleming
Julian Caird
Guy Bannister
Poppy Levine
Herbert Evans
Sydney Parsons
Sir Herbert Farquharson
Chief Commissioner
Hannen Swaffer
Vernon Bartlett
Eric Dunstan
Gillie Potter
Elisabeth Welch
Eve Becke
Gershom Parkington
Percival Mackey
Joseph Higgins (uncredited)
Police Doctor (uncredited)
Foreigner (uncredited)
Weisskopf (uncredited)
Man on BBC Reception Desk (uncredited)
Detective (uncredited)
Peter Ridgwell (uncredited)
Wife's Lover on Broadcast (uncredited)
Director
Director of Photography
Adaptation
Novel
Novel
Production Supervisor
Assistant Director
Art Direction
Sound Recordist
Editor
Costume Design
Music Director
Original Music Composer