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

Finlay Currie

Merchant Captain

Brefni O'Rorke

Detective Inspector Burrows

Ian Fleming

Kynaston Reeves

Naval Officer in Charge of Court Martial

Herbert Lomas

Van Driver

Terence de Marney

Code Expert

Charles Victor

Pub Owner

Anthony Dawson

2nd Code Expert

Alf Goddard

One of Mansel's Tough Friends (uncredited)

Jack Melford

Defence Lawyer at Court Martial (uncredited)

Hay Petrie

Waiter (uncredited)

Dennis Wyndham

George the Barman (uncredited)