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 won't trust anyone". A poor working relationship quickly developed between Sellers and Welles: Sellers eventually demanded that the two should not share the same set. Sellers left the film before his part was complete. A further agent's part was then written for Terence Cooper, to cover Sellers's departure. Shortly after leaving "Casino Royale", Sellers was appointed a Commander of the Most Excellent Order of the British Empire (CBE) in honour of his career achievements. The day before the investiture at Buckingham Palace, Sellers and Ekland argued, with Ekland scratching his face in the process; Sellers had a make-up artist cover