And the An Education star admits she was wracked with nerves as she waited to find out whether her audition had been successful.
She says, "I'd auditioned twice and waited for a fortnight, and called my agent every two hours for two weeks - he almost sacked me. It was a huge, huge shock (when I found out I got the role) and I can't believe I'm going to be working with the people I'm going to be working with. I have a copy of it by my bed that I'm obsessively reading."
"I can't wait (to start filming), but I don't think it's happening until summer so it's a long time."