Sidney Lumet Director Albert Finney Hercule Poirot Actor Lauren Bacall Mrs. Harriet Belinda Hubbard Actor Martin Balsam Signor Bianchi Actor Ingrid Bergman Greta Ohlsson Actor Jacqueline Bisset Countess Andrenyi Actor Jean-Pierre Cassel Pierre Paul Michel, the Conductor (as Jean Pierre Cassel) Actor Sean Connery Colonel Arbuthnot Actor John Gielgud Mr. Beddoes Actor Wendy Hiller Princess Dragomiroff Actor Anthony Perkins Hector MacQueen Actor Vanessa Redgrave Mary Debenham Actor Rachel Roberts Hildegarde Actor Richard Widmark Ratchett, Cassetti Actor Michael York Count Andrenyi Actor Colin Blakely Mr. Hardman Actor George Coulouris Dr. Constantine Actor Agatha Christie Writer Paul Dehn Writer Anthony Shaffer Writer John Brabourne Producer Richard Goodwin Producer Richard Rodney Bennett Original Music Geoffrey Unsworth Cinematographer Anne V. Coates Film Editing Dyson Lovell Casting Tony Walton Production Design, Costume Design Jack Stephens Art Director