Keira Knightley is continually shocked by her open-minded mother - because the cheeky matriarch wants to know all about the screen beauty's sex life.

Knightley, 20, describes her mum Sharman MacDonald as a "chilled-out hippy", who has no problem talking about the earthier side of life with her daughter.

She says, "My mum's a bit mental in a good way.

"She would come up to my room and have me roll her cigarettes and then tell me to have one with her. We would always talk about sex."