"A California commercial pilot sees a telecast in London of an interview with Sir Mark Lodden at his home. The Canadian is convinced that the baronet is a fraud, and he is actually a look-alike actor named Frank Welney."
Dirk Bogarde
as Sir Mark Loddon / Frank Welney / Number Fifteen
Olivia de Havilland
as Lady Margaret Anne Loddon
Paul Massie
as Jeffrey Buckenham
Robert Morley
as Sir Wilfred
Wilfrid Hyde-White
as Hubert Foxley
Anthony Dawson
as Gerald Loddon
Richard Wattis
as The Judge
Richard Dimbleby
as Himself
Martin Miller
as Dr. Schrott
Millicent Martin
as Maisie
Toke Townley
as Associate
Deering Wells
as Editor
Bill Shine
as The Guide
Ivan Samson
as Admiral Loddon
Sebastian Saville
as Michael Loddon
Richard Pearson
as The Butler
Robert Shaw
as First Photographer
Geoffrey Bayldon
as Second Photographer
Gordon Sterne
as Maddox
Arthur Howard
as Car Salesman
Joyce Carey
as Miss Sykes
Josephine Middleton
as Mrs. Squire
Kenneth Griffith
as Fitch
Barbara Archer
as Barmaid
Tony Doonan
as Man at Bar
Vanda Hudson
as Girl in Street
Victor Harrington
as Barrister (uncredited)
Sam Kydd
as Newspaper Vendor (uncredited)
Reg Thomason
Christian Dior
Costume Design
Anthony Asquith
Director
Edward Wooll
Original Story
Robert Krasker
Director of Photography
Maurice Fowler
Set Dresser
Anatole de Grunwald
Screenplay
Irene Howard
Casting
Paul Sheriff
Art Direction
Frank Clarke
Editor
Benjamin Frankel
Compositor
Karl Tunberg
Pierre Rouve
Associate Producer
Robert Carrick
Sound Editor
J.B. Smith
Sound Mixer
A.W. Watkins
Sound Recordist
Joan Johnstone
Hairstylist
Producer
Bill Lodge
Makeup Artist
Music
David Middlemas
Assistant Director
Tom Howard
Visual Effects
Gerry Turner
Roy Parkinson
Executive In Charge Of Production