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 All Right Jack", Sellers starred in "The Mouse That Roared", a film in which Jean Seberg also appeared, and was directed by Jack Arnold. He played three leading and distinct roles: the elderly Grand Duchess, the ambitious Prime Minister and the innocent and clumsy farm boy selected to lead an invasion of the United States. The film received high praise from critics. After completing "I'm All Right Jack", Sellers returned to record a new series of "The Goon Show". Over the course of two weekends, he took his 16mm cine-camera to Totteridge Lane in London and filmed himself, Spike Milligan,