Guy Hamilton Director Peter Ustinov Hercule Poirot Actor Colin Blakely Sir Horace Blatt Actor Jane Birkin Christine Redfern Actor Nicholas Clay Patrick Redfern Actor Maggie Smith Daphne Castle Actor Roddy McDowall Rex Brewster Actor Sylvia Miles Myra Gardener Actor James Mason Odell Gardener Actor Denis Quilley Kenneth Marshall Actor Diana Rigg Arlena Marshall Actor Emily Hone Linda Marshall Actor John Alderson Police Sergeant Actor Paul Antrim Police Inspector Actor Cyril Conway Police Surgeon Actor Barbara Hicks Flewitt's Secretary Actor Richard Vernon Flewitt Actor Robert Dorning Concierge Actor Dimitri Andreas Gino Actor John Brabourne Producer Richard Goodwin Producer Anthony Shaffer Screenwriter Christopher Challis Cinematographer Richard Marden Film Editing Cole Porter Original Music Elliot Scott Production Design Alan Cassie Art Director Peter Howitt Set Decoration Anthony Powell Costume Design