Sophia Loren as Nora Van Ostamgen

George Peppard as Lt. John Curtis

Trevor Howard as Professor Lindemann

John Mills as General Boyd

Richard Johnson as Duncan Sandys

Tom Courtenay as Robert Henshaw

Jeremy Kemp as Captain Phil Bradley

Anthony Quayle as Bamford

Lilli Palmer as Frieda

Paul Henreid as General Ziemann

Helmut Dantine as General Linz

Barbara Rütting as Hannah Reitsch

Richard Todd as Wing Cmdr. Kendall

Sylvia Syms as Constance Babington Smith

John Fraser as Flight Lt. Kenny

Maurice Denham as RAF Officer

Patrick Wymark as Prime Minister Winston Churchill

Wolf Frees as German Police Inspector

Moray Watson as Col. Kenneth Post

Richard Wattis as Sir Charles Sims

Allan Cuthbertson as German Technical Examiner

Karl Stepanek as Prof. Hoffer

William Mervyn as Dutch Technical Examiner

Milo Sperber as German Hotel Porter

George Mikell as German Officer

Ferdy Mayne as German Officer

Robert Brown as Air Commodore

Anton Diffring as SS Sturmbannfuhrer

Philip Madoc as German Police Officer

John Abineri as German Policeman

Charles Lloyd Pack as Technical Examiner

Gertan Klauber as Soldier at Rocket Plant

Jeremy Spenser as SS Officer at Rocket Plant

John Ronane as RAF Dakota Pilot