Keira Knightley has complained that people will not appreciate her films fully if they know too much about her private life.

She said: "No actor particularly likes talking about their private life, I think partly it ruins that magic of the films.

People that go and see it should get completely lost and believe that these people are real and I think it helps not to know anything about the background of the person."

Her new film The Duchess, a lavish melodrama of aristocratic foolishness and betrayal is designed around the colourful life of an 18th century socialite, Georgiana Cavendish, Duchess of Devonshire.

A feminist before the word was invented, Georgiana established a salon devoted to the artists and politicos of her day and even campaigned for Whig party candidates despite not having the vote herself.

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