In the current age of Internet celebrity, when Full Disclosure seems to be the default position of everyone, it's interesting looking back to the early years of Hollywood. Part of the allure of stars like Greta Garbo, Humphrey Bogart, Bette Davis and Marilyn Monroe, was that we seemed to know so little about them. And none were bigger than Hitchcock's favourite star, Cary Grant. Simon Morris picks up the story with Mark Kidel, director of the new documentary Becoming Cary Grant.