London, Oct 19 (ANI): Keira Knightley might be lady-like in appearance, but the actress' behaviour was anything but suave when she swore on the set of her latest film The Duchess.

The Oscar-nominated actress, who plays Georgiana, the fifth Duchess of Devonshire and great-great-great-great aunt of Diana, Princess of Wales, swore and burst into a laughing fit after messing up her lines during a crowd scene in a London set.

The British actress has confessed in the past that she detests the early days of filming and feels panicky in front of a crowd.

"I fear everything. New characters, new parts, first days of filming and premieres always terrify the life out of me. Small things terrify me: If I go out, I never know what to say," the Daily Mail quoted her, as saying.

"I always feel self-conscious," she added.

The Duchess has been adapted from Amanda Foreman's biography of the 18th century aristocrat, who endured her husband, the Duke of Devonshire's affair with her best friend, Lady Elizabeth 'Bess' Foster.

Ralph Fiennes is playing Knightley's on-screen husband, while Charlotte Rampling is playing Lady Spencer. (ANI)