Bryan Forbes Director, Producer John Mills Masterman Finsbury Actor Ralph Richardson Joseph Finsbury Actor Michael Caine Michael Finsbury Actor Nanette Newman Julia Finsbury Actor Peter Cook Morris Finsbury Actor Dudley Moore John Finsbury Actor Tony Hancock Detective Actor Peter Sellers Doctor Pratt Actor Cicely Courtneidge Major Martha Actor Wilfrid Lawson Peacock Actor Thorley Walters Lawyer Patience Actor Gerald Sim First Undertaker Actor Peter Graves Military Officer Actor Irene Handl Mrs. Hackett Actor Norman Bird Clergyman Actor John Le Mesurier Doctor Slattery Actor Hilton Edwards Lawyer Actor Norman Rossington First Rough Actor Diane Clare Mercy Actor Tutte Lemkow Strangler Actor James Villiers Sydney Whitcombe Sykes Actor Jeremy Lloyd Brian Allen Harvey Actor Leonard Rossiter Vyvyan Alistair Montague Actor Valentine Dyall Oliver Pike Harmsworth Actor Larry Gelbart Producer Burt Shevelove Producer John Barry Original Music Gerry Turpin Cinematographer Alan Osbiston Film Editing Weston Drury Jr. Casting Julie Harris Costume Design