Peter Ustinov as Marcus Pendleton / Caesar Smith

Maggie Smith as Patty Terwilliger Smith

Karl Malden as Carlton J. Klemper

Bob Newhart as Willard C. Gnatpole

Robert Morley as Caesar Smith

Cesar Romero as Customs Inspector

Elizabeth Counsell as Miss Glyn

Margaret Courtenay as Mrs. Hubbard

Lynda Baron as Louise the Waitress

Sean Barry-Weske as Hippie in Boutique

Paul Dawkins as Pritchard

Paul Farrell as Larry

Raymond Huntley as Bayswater

Peter Jones as Prison Governor

Anthony Sharp as Hollis

Kynaston Reeves as Quayle