Munro's big break came in March 1958 when she was cast as Katie O'Gill in Disney's Darby O'Gill and the Little People (1959). Disney immediately used her again as the Lizbeth Hempel in Third Man on the Mountain (1959) opposite James MacArthur. Munro returned to England to play Tommy Steele's love interest in Tommy the Toreador (1959), then made a third film for Disney, Swiss Family Robinson (1960), again romancing MacArthur. Munro was going to be in Bon Voyage! with Karl Malden but it was not made for another few years, with Deborah Walley in the role announced for Munro. Instead she appeared in The Horsemasters (1961), shot in England for American television, and released theatrically in some markets.
Munro died on December 6, 1972 on her way to the hospital after collapsing at her London home in Tufnell Park. Her death was ruled due to a heart attack caused by chronic ischemic heart disease. She was aged 38 years. She was cremated and interred at the Golders Green Crematorium.