According to the Turner Classic Movies website, O'Toole had been eager to work with Glenville, a friend of his, on the film and make it as a "straight" non-musical drama, but was highly displeased when Glenville was fired and replaced by Arthur Hiller, referring to him constantly as "little Arthur". However, according to Saul Chaplin's autobiography, O'Toole, who could not sing, assisted in the search for a voice double when he realized the film would indeed be a musical after all, eventually finding Simon Gilbert. In his autobiography "Absolute Pandemonium", Brian Blessed claims to have dubbed the singing voice of Harry Andrews as well as appearing onscreen as Pedro.