The movie was popular at the box office in Britain. Disney Bill Anderson, one of Walt Disney's producers, saw Tiger Bay and suggested that Mills be given the lead role in Pollyanna (1960). The role of the orphaned "glad girl" who moves in with her aunt catapulted her to stardom in the United States and earned her a special Academy Award of Juvenile Oscar, the last person to won the accolade. Because she could not be present to receive the trophy, Annette Funicello accepted it on her behalf. Disney subsequently cast Mills as twins Sharon and Susan who reunite their divorced parents in The Parent Trap (1961). In the film, she sings "Let's Get Together" as a duet with herself. The film was a hit around the world, reaching number 8 on a US Top Ten list. Mills received an offer to make a film in Britain for Bryan Forbes, Whistle Down the Wind (1961), based on a novel by her mother Mary Hayley Bell, about some children who believe an escaped convict is Jesus. It was a hit at the British box office and she was voted the biggest star in Britain for 1961. Mills was offered the title role in Lolita by Stanley Kubrick, but her father turned it down. "I wish I had done it", she said in 1962. "It was a smashing film." Mills returned to Disney for an adventure film, In Search of the Castaways (1962), based on a novel by Jules Verne. It was another popular success, and she was voted the fifth biggest star in the country for the next two years. In 1963, Disney announced plans to film an adaptation of Dodie Smith's novel I Capture the Castle, with Mills in the role of Cassandra. Disney ended up dropping the project, while still retaining film rights to the book, when the novelist and the selected screenwriter Sally Benson did not get along; Mills grew too old for the part before the project could be revived. Her fourth movie for Disney did less well than her previous Disney films, but was still successful: Summer Magic (1963), a musical adaptation of the novel Mother Carey's Chickens. Ross Hunter hired her for a British-American production The Chalk Garden (1964), playing a girl who torments governess Deborah Kerr. Back at Disney she was in a film about jewel thieves, The Moon-Spinners (1964), getting her first on