I was sad to leave 'Downton,' but I will always remember it fondly, as they did me a lot of favours. I owe them a lot.

Playing Sgt, Trotter in 'The Mousetrap' is the same as playing Scripps in 'The History Boys,' in the sense that they're dream roles that I've always wanted to do. The fact they're letting me do this professionally and I'm getting paid for it, I find astonishing.

I actually did an Agatha Christie monologue for my audition showcase at Guildhall, and that's how I got my agent. Some people said 'ooh it's old hat' and 'too risky'. Some people think she's all about the narrative and thriller aspect at the expense of character and I disagree. I did it anyway and it worked well.