A NNA Karenina is commonly regarded as one of the great romantic heroines of literature. In Leo Tolstoy's Russian classic, Karenina leaves her husband and children for her lover despite the obvious consternation of friends, family and society. And so thought Keira Knightley when she landed the part, before she reread the weighty tome. ''I think Tolstoy is absolutely making the moral point that you shouldn't do what she does,'' she says. ''I think she is the anti-heroine.
''From my sensibility and a modern sensibility, that's not how I feel at all. I think if you feel trapped in a relationship that doesn't work for you, then you need to do something about that. But that is a very modern sensibility.''
Her outlook of the character became far more realistic than idealistic. ''Romance is part of love - it's just not the only part of love,'' she says. ''Her tragedy is that she can't recognise any other part of love.
''So when it is less than that immediate romance, she thinks that it's disappeared, and therefore she has failed, and therefore everybody is against her and therefore she is on her own, which is the tragedy of the piece.''
Despite claiming to have a modern outlook, the 27-year-old believes in the institution of marriage. In May the London girl became engaged to Klaxons keyboardist James Righton. It was one of those strange quirks of life that she was heading towards nuptials while playing a woman breaking her vows. ''I didn't realise while I was playing the character that I was moving towards getting married myself,'' she says. Shooting wrapped before the proposal came.
''When playing characters in general, you use less of your own life experience and more of your life understanding. You can be in a happy place and play an incredibly infectious, miserable character, or vice versa.'' Although the character did consume her while filming.
''I don't think I was the easiest to live with when we were shooting. She came home more than I would have liked [her] to,'' she says, adding: ''I was just in a bad f---ing mood.''
The actor peppers our conversation with expletives. There's a forthrightness in her responses - she doesn't seem to have a filter. She's wearing a black dress and when asked if it's Chanel, with whom she has a lucrative contract, she bounces back: ''I'm not sure, I had to do a last-minute swap of clothing. Why don't we just pretend it is? No one will know.''
Anna Karenina reunites British director Joe Wright and Knightley for their third feature film together. She says of her relationship with the Pride and Prejudice and Atonement director: ''It is intimate because he is a friend and we know each other quite well. We live quite close to each other and we see each other an awful lot. What I think was more interesting this time was that we expected it to be exactly as it was and I don't think we realised that it's actually been five years since the last film we did - we have done adverts and little bits but not a film.
''I think we both went, 'Oh, you've changed.' But I think that was also a lot to do with the character.''
Having originally planned to shoot in Russia, Wright soon realised that all the best locations had already been used in previous movie adaptations. He then came up with the idea of filming much of the production on a sound stage in London and in the opening scene we see the theatrical set being moved in the background as characters traverse from one location to another.
Knightley was a big fan of the heavily stylised aesthetic: ''It was actually one of the reasons it was so exciting to do it … It was really hard because you want this stylised piece, but you don't want to lose the emotional impact of the characters, in particular with Anna.''
Anna Karenina opens in cinemas on February 14.