Sienna Miller

Sexy Sienna Miller agreed to go topless as artist Andy Warhol's muse Edie Sedgwick in new movie Factory Girl after coming to terms with the socialite's drug-addled depression.

The actress researched her role by talking to Sedgwick's husband and brother and realised she wouldn't be doing the model justice if she kept her clothes on for degrading drug and sex scenes in the film.

Miller explains, "I think it was important to see Edie at her most vulnerable, in order to understand her fall and to empathise with her when she was really down and out and not glamorous."

"Everybody thought it was important to see her looking glamorous and attractive, so that when you see her heroined out in the bed at the end (of the film) it's a shock."

"You see her opening up to a man, which, for her, was a hard thing to do. If you're gonna do a sex scene you might as well do it. I'm not gonna have sex with a bra on because people don't."