- Jack Hawkins
- Insp. George Gideon
- Dianne Foster
- Joanna Delafield
- Cyril Cusack
- Herbert 'Birdie' Sparrow
- Anna Lee
- Mrs. Kate Gideon
- Anna Massey
- Sally Gideon
- Andrew Ray
- PC Simon Farnaby-Green
- James Hayter
- Robert Mason
- Ronald Howard
- Paul Delafield
- Howard Marion-Crawford
- Chief of Scotland Yard
- Laurence Naismith
- Arthur Sayer
- Derek Bond
- Det. Sgt. Eric Kirby
- Griselda Harvey
- Mrs. Kirby
- Frank Lawton
- Det. Sgt. Frank Liggott
- John Loder
- Ponsford (the Duke)
- Marjorie Rhodes
- Mrs. Rosie Saparelli
- Hermione Bell
- Dolly Saparelli (uncredited)
- Michael Trubshawe
- Sgt. Golly
- Jack Watling
- Rev. Julian Small
- Henry B. Longhurst
- The Vicar (uncredited)
- Michael Shepley
- Sir Rupert Bellamy
- Nigel Fitzgerald
- Insp. Cameron (uncredited)
- Robert Raglan
- Dawson (uncredited)
- Maureen Potter
- Ethel Sparrow (uncredited)
- Doreen Madden
- Miss Courtney
- Miles Malleson
- Judge at Old Bailey
- John Ford
- Director
- T.E.B. Clarke
- Writer
- John Creasey
- Writer
- Michael Killanin
- Producer
- Wingate Smith
- Associate Producer
- Douglas Gamley
- Original Music
- Freddie Young
- Cinematographer
- Charles Lawton Jr.
- Cinematographer
- Raymond Poulton
- Film Editing
- Ken Adam
- Art Director
