James Mason
Cmdr. Max Easton
George Sanders
Sir Charles Holland
Frederick Piper
Hall Porter (uncredited)
Richard Marner
Russian Officer Cornered by Max Easton (uncredited)
Vera Miles
Virginia Killain
John Le Mesurier
Head of the Admiralty (uncredited)
Harry Andrews
Capt. Graham
Charles Carson
Robert Holland
Oliver Johnston
Minister
Duncan Lamont
1st Special Branch man Gregson
Ronald Leigh-Hunt
2nd Editor (uncredited)
Robert Flemyng
Cmdr. John Larkin
Gordon Harris
2nd Special Branch Man Jones (uncredited)
William Mervyn
Capt. Balfour (uncredited)
John Horsley
1st Editor (uncredited)
Martin Stephens
John Holland
Barbara Hicks
Miss Price (uncredited)
Mavis Villiers
Adele Parrish
Dickie Owen
2nd Policeman (uncredited)
Henry B. Longhurst
Club Member (as Henry Longhurst)
Basil Dignam
Lt. Cmdr. Evans at P.R.O. (uncredited)
MacDonald Parke
Jason Parrish (as Macdonald Parke)
Ernest Clark
Cmdr. Bates
Donald Bisset
Club Member
Desmond Roberts
Club Member
Peter Barkworth
Sub Lt. Brown
Junia Crawford
Susan
Andre Mikhelson
2nd Russian Officer (uncredited)
Alexander Archdale
Local Doctor (uncredited)
Rachel Gurney
Clara Holland
Reginald Smith
Club Steward
Waveney Lee
Marcia Holland
Pat Ryan
Nightclub Patron (uncredited)
Rosemary Dorken
WREN Officer
Mabel Etherington
Nightclub Patron (uncredited)
John More
American General at Embassy Party (uncredited)
Frederick Kelsey
Club Member (uncredited)
Stanley Zevic
1st Russian Officer (uncredited)