Keira Knightley considered retiring when she was 22.

The 25-year-old actress revealed she wasn't happy with her career and felt she had missed out on a normal life but the chance to work with fellow British star Carey Mulligan on 'Never Let Me Go' changed her mind.

She told Britain's Vogue magazine: "I didn't know if I was going to go back to acting at all. I think for a long time I thought I wouldn't. I think I intended not to work again."

"Carey's a very good friend of mine and I felt if I was to start making films again, she was someone who would watch my back."

Keira - who is in a relationship with actor Rupert Friend - explained she considered quitting acting is because she had become disillusioned with her privileged life but also because she was desperate to go on vacation.

She said: "I wasn't enjoying what I was doing and I felt terribly guilty about that.

"I remember hating the idea that I was in a privileged position and couldn't see the point of any of it.

"I had worked solidly since I was 16, till 22, and I had not been on holiday in all of that time."