The story of Mary Poppins, the quintessentially English and utterly magical children's nanny, is remarkable enough. She was instantly hailed as a classic, then became a household name when Julie Andrews stepped into the role in Disney's hugely successful film. Now she is a Broadway sensation all over again. But the story of Mary Poppins's creator, as this first biography reveals, is just as unexpected and remarkable. Australian journalist Pamela Lyndon...