Once you start [filming] you have researchers who are constantly giving you information. Ultimately it isn't about impersonating or trying to be an image of somebody and more trying to capture the spirit and the soul of the person somehow.

[Queen Elizabeth] is just the granny queen! She's our granny queen who shakes people's hands!

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!

Marking the differences between them was really important. It just became second nature. When we were choosing pajamas or something, instantly you'd be able to spot: those are [princess] Margaret, those are [princess] Elizabeth. It became this sort of language, really, of the two sisters.

Once you start [filming] you have researchers who are constantly giving you information. Ultimately it isn't about impersonating or trying to be an image of somebody and more trying to capture the spirit and the soul of the person somehow.

I knew she was a party girl. The book I liked most on her was called [princess] Margaret: A Life of Contrasts and getting to know her, it was how conflicted her position and her internal life - or self - was. She is so fiercely royal and so fiercely "sister of the queen" or "daughter of the king" because that is her identity and it's all she's ever known. And at the same time she is struggling to push the boundaries and to break away from it, to be different or to modernize the monarchy, to turn it on its head.

It was always said you couldn't have two sisters less alike. In a way [princess] Elizabeth was always internalizing everything and [princess] Margaret was always externalizing everything, so that became the basis. The storyline becomes about these two sisters: they're fighting for their position or trying to establish their identity in the world alongside each other and in relation to this establishment which only those two were a part of.