"Everybody has an image of [princess Margaret], to a certain extent. But I felt it would have been harder if we were playing them as they are now. In a way, I don't know how much of a living memory we as a collective have of them in the '50s, when Margaret was 21 and this sort of Elizabeth Taylor. You don't think of your grandparents as being teenagers. You just can't - your brain just can't go there!"