ABOVE: Dress, £2,365, Marni (net-a-porter.com)

You mention turning 30. Do you feel like you’re developing into someone different with age?

I was mad until I was about 25.

In what way?

Completely out of control with my emotions. Everything that happened to me was a tragedy. I’ve been much happier as a person over 25. That exhausting pressure of having to be beautiful? Thank god that’s over. I can’t wait until I’m 50. I can’t wait until people stop worrying about that. I think for some women it carries on, but for me it just seems to have lifted. Although the parts get fewer, that’s definitely true, they can get better as well, because you’re not playing romantic leads opposite men. You’re playing characters in their own right.

Your character Sugar in The Crimson Petal And The White took part in some explicit scenes. Did you watch any of them back?

I watched it back and was like, “God I look amazing!” [Laughs] I didn’t watch it back, no. I trusted the director [Marc Munden] and I don’t really have a problem being naked on screen. Obviously, people can perv over it if they want to. But it’s all about the way your body is represented. If it’s highly sexualised then that’s not serving the story. Otherwise your body is just part of yourself. With that story, she was a prostitute. The only thing I stressed to Marc was how we needed to make it very clear that this is her job. It’s something she does proficiently but it’s not something she enjoys. All the pleasure she gets out of it, is the pleasure of a job done well. My worry was that when you represent prostitution on screen the mechanics of it are sidelined and it becomes a cipher for women being abused. I didn’t want it to just be something that’s referred to; what happens, how they have sex, what she gets paid, all the stuff to do with contraception was really important.

You don’t take the projects you attach your name to lightly…

I’m very interested in gender politics. So I won’t take parts that are bad or if the message is weird or I’m not comfortable promoting it. I’m not good at lying so if I think something is sh*t, I’m not going to be able to do it. I don’t want the rewards enough to go through that. If you desperately want to make a lot of money and be famous, there’s nothing wrong with that. That’s when you will do anything.

A lot was made of your sojourn in Hollywood [to make the not-so-good Dirty Dancing: Havana Nights in 2004]. Did that put you off?

That was like [eight] years ago now. I had a nice enough time, but haven’t been back. I’ve been very fortunate with my career, so the imperative to go and look for work in America isn’t always great if you feel fulfilled by the career you already have. At the risk of saying something that’s going to make me entirely loathed, I haven’t had to worry about work. The longest I’ve been really out of work is four or five months. For my line of work that’s a very manageable amount of time.

How do you fill four or five months?

I don’t have any trouble. When I get a job after a break, I wonder how I will do everything. By the time I’ve done the housework, gone to see friends, kept up with my family, read all I want to read, done my paperwork…

What do you read?

I just finished reading The Memoirs Of A Survivor by Doris Lessing. It was amazing. I’m really into apocalyptic fiction. What did I read before that? I have literary amnesia. But I also go to the cinema and the theatre a lot. I’m always destroyed by jealousy when I see something really good but I’m a real culture vulture. I like swimming too. It’s good if you’re trying to do anything creative. If I just go up and down 50 times, quite often at the other end I’ve got something in my head I think I can create.

Would you say you’re quite present then; not a daydreamer?

I’m a busy person. I’m terrible at yoga. I’m miserable when my mind is clear. I love to be distracted and have lots on. I’m not a person who is happier having an empty head.

The Hour starts on BBC 2 in November

Romola Garai: no wallflower