According to the New York Post, she will star in the play in the West End under the direction of Ian Rickson. No official announcement about the production has been made.

Originally premiered on Broadway in 1934, The Children's Hour was last produced in London at the National's Lyttelton Theatre in 1994, in a production that featured Emily Watson, Harriet Walter and Clare Higgins. The play is set set in an all-girls boarding school run by two women, Karen Wright and Martha Dobie. An angry student, Mary Tilford, runs away from the school, and to avoid being sent back she tells her grandmother that the two headmistresses are having a lesbian affair. The accusation proceeds to destroy the women's careers, relationships and lives.

Knightley previously appeared on the West End stage in The Misanthrope that opened in December 2009 at the Comedy Theatre, running through March 2010. She is best known for her film appearances in "Bend It Like Beckham," "Atonement" with James McAvoy, "The Duchess," "The Edge Of Love" with Sienna Miller, "Domino," "The Jacket," "Pride And Prejudice" (for which she was Oscar-nominated), as the feisty Elizabeth Swann in the "Pirates of the Caribbean" movies, and in the recently released "Never Let Me Go."