James Mason
Richard Francis Heritage
Joyce Howard
Laura Verity
Tom Walls
Christopher Child
Phyllis Stanley
Lily Bernard
Edward Rigby
Mansel
Ronald Ward
Carter
David Farrar
Commander Lippinscott
Karl Stepanek
Riccardo
Betty Warren
Fay
Walter Crisham
Charlie
Jeanne De Casalis
Lady with Dog
Patricia Medina
Mary, Manicurist (as Pat Medina)
George Robey
Pawnbroker
Ronald Chesney
Max - Mouth Harmonica Player
Peggy Dexter
Bobby
Finlay Currie
Merchant Captain
Brefni O'Rorke
Detective Inspector Burrows
Eric Mason
Benson - Illusionist
Anthony Holles
Hotel Hairdresser
Kynaston Reeves
Naval Officer in Charge of Court Martial
Herbert Lomas
Van Driver
Percy Walsh
Police Sergeant
Terence de Marney
Code Expert
Charles Victor
Pub Owner
Robert Sansom
Petty Officer Bill Grant
Alvar Liddell
Boothby - Radio Announcer
Anthony Dawson
2nd Code Expert
Alf Goddard
One of Mansel's Tough Friends (uncredited)
David Keir
Henry (uncredited)
Jack Melford
Defence Lawyer at Court Martial (uncredited)
Hay Petrie
Waiter (uncredited)
Leonard Sharp
Bus Conductor (uncredited)
Dennis Wyndham
George the Barman (uncredited)