Sienna Miller stepped out with her elder sister Savannah at the UK premiere of Factory Girl at Vue West End on Tuesday evening in London, England. Savannah is a co-designer of the Miller sisters’ fashion line, Twenty8Twelve.

Sienna had jaws dropping at the New York premiere in January when she showed up to the after-party in a pair of black granny panties and…well…not much else!

She later explained the outfit was a homage to Andy Warhol’s muse, Edie Sedgwick.