When I started drama school, theatre was the main draw. I never had any movie star notions. Not that there were family ties to the theatre, either.

The life of an actor is very random. It can be exhilarating but terrifying - you do wonder day to day where the next job will come from. Some of my friends are very talented people, but you see them out of work - which can be tough. If you wanted that kind of security, though, I guess you wouldn't be an actor in the first place.

I only went along to youth theatre with a friend when I was young to try to make myself a bit more sociable. But the whole thing was quite sore; it really hurt me trying to get into drama school. It was a world I knew nothing about - it was very middle class; all that usual stuff. But I was young, determined, and I just went for it.

That's the thing - you do a job like 'Shameless,' and suddenly that's why you can get a job like 'The Virgin Queen', not because of all the classical theatre you've done. But we can be very snippy about television. It's absolutely the most potent and powerful form of storytelling we have.

There are some roles you just don't say 'no' to. Those compass points: you get them so rarely as an actress.

For actors, being successful is generally getting a job. If you can work a lot, you're really successful. If you work a lot on projects that are interesting and intelligent and great fun to be part of, then you're hugely successful. And I feel hugely successful. I can't believe that I get to be involved with the projects and the people I work with.

In theatre, there's the director, the writer, and below them the actor. In film, it's the actors who are most important. That goes against the grain for me.