Christie was born in Chabua, Assam, India, then part of the British Empire, the first of two children of Rosemary (née Ramsden) and Frank St. John Christie. Christie's mother was a Welsh-born painter and childhood friend of actor Richard Burton, while Christie's father ran the tea plantation around which Christie grew up. She had a brother and a half-sibling from her father's affair with an Indian mistress. Christie's parents separated during her childhood. She was baptized in the Anglican church, and studied as a boarder at Convent of Our Lady School in St Leonards-on-Sea, East Sussex, (from which she was later expelled), and then at Wycombe Court School in High Wycombe, Buckinghamshire, also living with a foster mother from the age of six. After her parents' divorce, Christie spent time with her mother in rural Wales. As a teenager at Wycombe Court School, she played the role of the Dauphin in a school production of George Bernard Shaw's "St. Joan". She later studied at the Centr