Monday 12th February at 9pm on BBC Two

How did it  feel to be taking on a role in a David Hare drama?
It’s funny because before I worked with him, David Hare was the famous writer whose plays, films and work I had always loved - and so it is extremely weird to be suddenly talking about and be involved in something he has created. It's thrilling and I couldn’t agree more with what people say about David’s ability to write incredible female characters. He really does flesh out the complexities of a woman as well as some of the ugliness.

What it was about the role of Karen Mars that attracted you?
I liked that Karen was a complex woman, I always find that the most appealing thing in a script. She has obviously lived a difficult life and has been damaged by her past. She has lived with addiction and a devotion to a man who didn’t love her and, unsurprisingly, she isn’t a particularly nurturing mother. It is Karen who kick-starts this entire story; she gets it all rolling and she is such a great character - a woman of many faces who is beautifully written.

Were you pleased to  be reunited with John Simm on this project?
I've known John since I was 16 and I have admired him as an actor since I first saw him in Human Traffic. He is one of those very rare, down-to-earth men who also happens to be an actor. He is a man before he is an actor which is something I always find really refreshing.

My character and John’s character share a volatile relationship in the drama: it’s sexy and aggressive, it's loveless, but it is her passion. She lives to pursue this dead love, and it's really tragic. John’s role is a brilliantly written part as well - he has this very important job as a politician but here we see him be vulnerable and make mistakes.

How did you find filming in London?
I have a love affair with London I can’t ever shake. It always impressed me so much growing up, and I have always felt so lucky to live and work here. There have been a lot of things recently that have made London feel more threatening than it has normally but I am behind it and I believe in the city. I am not going anywhere.

There are lots of things about London that blow my mind, that I can never get over. I am from a small town that looks totally different to London, so I was always shocked as a child how somewhere that was only 50 minutes down the motorway could be so different in culture, diversity and opportunity, and how it could contain so many different worlds, all coexisting. It still blows my mind.

This show encapsulates all of that. It shows London in all of its ugly truths and, at times, it feels very underworld even though these are things that are happening on our streets all the time at the moment. The drama is a controversial, state of the nation piece and also a thriller which, if written well, are two things which coexist beautifully.