Keira Knightley graciously agreed to sign autographs for enthusiastic fans - while standing naked in a gymnasium-changing room.

The King Arthur star, 19, was approached by a group of female admirers while in the nude at the Amida Health Club in Hampton, near London, and she signed their pieces of papers before getting dressed.

A source says: "These girls spotted her in the changing room and couldn't wait to go over to meet her, even though she didn't have her clothes on.

"Keira just acted like a true professional and got on with it.

"Word soon got round the club about what she'd done and no one could believe just how nice and down-to-earth she is that she didn't mind doing that."