she said on her twitter or similar that it was for french vogue, and that the photographer wanted her to be sexy- which she despised- however she said that after a chat with the photographer, she found she doesn't fear sexiness, just what it represents, like the pornification of today's kids, and now is embracing "sexiness".
Sorry to be vague where this comes from, but I read it in quite a few sources- her twitter, an interview etc
She's been given Chanel for quite a while to wear now. Also in British Elle, when Henry Holland interviewed her when she was on the cover, she said that Karl said "I hate all these people here. But not you, I only like you" (again, possibly not the EXACT quote she used, but along those lines)