Sienna Miller in Balenciaga at the American Sniper premiere in New York
Sienna Miller's nothing if not a trendsetter. Despite her protestations otherwise, the actress pretty much invented boho; she was one of the first to wear leggings outside of the gym, and the only person ever to make it acceptable to wear a large pair of pants as partywear.
If you can't remember the garment in question, cast your mind back to 2007 and to the Factory Girl after party where she wore a pair of Bridget Jones-esque knickers with a fluffy jumper on top.
The outfit may have split opinion, but it definitely made headlines. And now it seems the star has found a brand spanking new white pair just in time for her American Sniper promo tour.
This time around however, Sienna has opted to try out a more grown up take on the trend, opting to wear her undergarments underneath her gorgeous Balenciaga dress, rather than alone over a pair of 60 deniers.
We're not undecided on whether this outfit works or not: we think Sienna looks stunning.