At the same time, [princess Margaret] had a fragility and an insecurity in who she was and her position, because her sister had always got the education ever since David [Edward VIII] abdicated.

Some of the biographies [of princess Margaret] were really sensationalist, News of the World sorts, but they were great because they also gave first and secondhand accounts of her at home. The butlers come forward and give little moments, some of which you discard and some which ring somehow true and you use.

People are so much more fascinated by the royal family generally than in England.

I watched tons of archive footage of princess Margaret and listened to the music she loved; that was really immersive and brilliant.

That's exactly how I felt. So getting to suddenly know this young [princess] Margaret, who had this extraordinary life - it was sad and tragic and difficult and sort of astonishing and getting to know her young self was amazing because it completely defied all my expectations.

At the same time, [princess Margaret] had a fragility and an insecurity in who she was and her position, because her sister had always got the education ever since David [Edward VIII] abdicated.

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!