Terry Southern of the Monty Python team. Cleese later described McGrath as having "no idea of comedy structure" and complained that the film ended up as "a series of celebrity walk-ons." The film was shot in London between February and May 1969. The cast was headed by Sellers (as Guy Grand) and Ringo Starr as his son Youngman Grand (a new character created for the movie), with cameo appearances by Spike Milligan, Christopher Lee, Laurence Harvey, Raquel Welch, Roman Polanski and Yul Brynner. As with "Dr Strangelove", Sellers habitually improvised on the script during filming. During production McGrath and Southern discussed a
Peter Sellers and abilities were unimpaired after the experience of filming. Sellers followed this with the role of the perverted Austrian psychoanalyst Doctor Fritz Fassbender in Clive Donner's "What's New Pussycat?", appearing alongside Peter O'Toole, Romy Schneider, Capucine, Paula Prentiss and Ursula Andress. The film was the first screenwriting and acting credit for Woody Allen, and featured Sellers in a love triangle. Because of Sellers's poor health, producer Charles K. Feldman insured him at a cost of $360,000 ($ in dollars). Sellers became a close friend of Antony Armstrong-Jones, 1st Earl of Snowdon, a photographer who was then married to Princess Margaret.