Sienna Miller Is a High-Street Girl at Heart

In the United Kingdom, one Rosie bra is sold in Marks & Spencer every 30 seconds. First launched in 2012 as part of a collaborative lingerie line designed by the model Rosie Huntington-Whiteley, the high-street retailer—beloved for its grandma-ish twin sets in the 1980s and middle-class picnic snacks in the 2020s—has been hoping to recreate that winning formula with a series of ready-to-wear collections made with Sienna Miller.

Following the success of her first edit back in June, the actor has unveiled a 35-piece party collection built from her own archive of vintage Portobello Market finds. There are velvet blazers, tiger-striped waistcoats, ruffled blouses and one lime-green dress to rival Victoria Beckham’s cult spring 2023 creation. “There’s no one that does undone, relaxed chic like the Brits,” Miller not long ago informed a room of gathered journalists at Marks and Sparks’s HQ. “I think it’s something to do with the irreverence and the English sense of humor.”

Last night, Miller headed to the launch of her sophomore collection in a Bianca Jagger-inspired M&S trouser suit—“No one partied like they did then, so I tried to capture that spirit,” she said in a release—with a tacky-fab clutch tucked inside her arm. It’s the high-low thing that feels particularly British here. To wit: Jonathan Anderson referenced Marks’s multi-pack vests within his fall 2024 collection, while an impervious editor of mine used to clack around Paris Fashion Week in second-hand skirts from Per Una—Marks and Spencer’s frilliest and perhaps also frumpiest sub-brand—with vicious Jimmy Choos kitten heels. She looked good.