Steven Moffat is one of a select band of writers and producers who is almost as famous as the stars who appear in his shows.

Not content with being the showrunner on the BBC's biggest-selling global hit, Doctor Who, he was also the co-creator, along with League of Gentlemen star Mark Gatiss, of one of BBC1's most acclaimed new dramas of last year, Sherlock.

Moffat, a long-time Whovian, began his TV career with the Bafta-winning children's show Press Gang and was best known for BBC2 sitcom Coupling before taking over from Russell T Davies on the time-travelling show. He also co-scripted new Steven Spielberg film, The Adventures of Tintin: The Secret of the Unicorn.

Karen read twice for him at auditions and he was impressed with her charisma and her natural instincts. "More importantly, she can do the text convincingly and she feels as if she comes from that Sixties British Mad Men world," Lloyd added.

Synopsis: Bill Maitland, a middle aged lawyer, struggles to avoid the harsh truths of his life and keep a hold on reality. As those closest to him begin to draw away, he puts himself on trial to fight for his sanity.

I left Doctor Who, because I could not get along with the senior people. I left, because of politics. I did not see eye-to-eye, with them. I didn't agree with the way things were being run. I didn't like the culture that had grown up, around the series. So, I left. I felt, over a principle. I thought to remain, which would have made me a lot of money and given me huge visibility, the price I would have had to pay, was to eat a lot of shit.

I'm not being funny about that. I didn't want to do that and, it comes to the art of it, in a way. I feel that if you run your career and-we are vulnerable as actors and, we are constantly humiliating ourselves auditioning. But, if you allow that to go on, on a grand scale. You will loose, whatever it is about you and, it will be present in your work.

If you allow your desire to be successful and visible and financially secure – if you allow that to make you throw shades on your parents, on your upbringing, then you’re knackered. You’ve got to keep something back, for yourself, because it’ll be present in your work. A purity or an idealism is essential or you’ll become– you’ve got to have standards, no matter how hard work that is. So it makes it a hard road, really.

You know, it’s easy to find a job when you’ve got no morals, you’ve got nothing to be compromised, you can go, ‘Yeah, yeah. That doesn’t matter. That director can bully that prop man and I won’t say anything about it’. But then when that director comes to you and says ‘I think you should play it like this’ you’ve surely got to go ‘How can I respect you, when you behave like that?’

So, that’s why I left. My face didn’t fit and I’m sure they were glad to see the back of me.

The important thing is that I succeeded. It was a great part. I loved playing him. I loved connecting with that audience. Because I've always acted for adults and the suddenly, you're acting for children. Who are far more tasteful, they will not be bullshitted. It's either good, or it's bad. They don't schmooze at after show parties, with cocktails.