Jack Arnold Director, Producer Peter Sellers Grand Duchess Gloriana XII, Prime Minister Count Rupert Mountjoy, Tully Bascombe Actor Jean Seberg Helen Kokintz Actor David Kossoff Professor Alfred Kokintz Actor William Hartnell Will Buckley Actor Timothy Bateson Roger Actor MacDonald Parke General Snippet Actor Monte Landis Cobbley Actor Leo McKern Benter Actor Harold Kasket Pedro Actor Colin Gordon BBC Announcer Actor Jacques Cey Ticket Collector (uncredited) Actor Bill Nagy U.S. Policeman (uncredited) Actor Mavis Villiers Telephone Operator (scenes deleted) Actor Leonard Wibberley Writer Roger MacDougall Screenwriter Stanley Mann Screenwriter Jon Penington Producer Walter Shenson Producer Carl Foreman Producer John Wilcox Cinematographer Raymond Poulton Film Editing Edwin Astley Original Music Geoffrey Drake Art Director