Clifton Webb as Lt. Cmdr. Ewen Montagu

Gloria Grahame as Lucy Sherwood

Robert Flemyng as Lt. George Acres

Josephine Griffin as Pam

Stephen Boyd as Patrick O'Reilly

Laurence Naismith as Adm. Cross

Geoffrey Keen as Gen. Nye

Moultrie Kelsall as The Father

Cyril Cusack as Taxi Driver

André Morell as Sir Bernard Spilsbury

Michael Hordern as Gen. Coburn

Allan Cuthbertson as Vice-Admiral

Joan Hickson as Landlady

Terence Longdon as Larry

Gibb McLaughlin as Porter

Miles Malleson as Scientist

William Russell as Joe

William Squire as Lt. Jewell

Richard Wattis as Shop Assistant

Ronald Adam as Adams

Robert Brown as French

Everley Gregg as Club Matron (uncredited)

Lloyd Lamble as Passport Officer (uncredited)

Brian Oulton as Wills Officer (uncredited)

John Welsh as Bank Manager

Peter Sellers as Winston Churchill (voice)