Though she is reportedly expecting her first child, Sienna Miller‘s fashion baby has already flown the coop. After six years as co-creative directors at Twenty8Twelve, she and sister Savannah have stepped down from their joint role at the label.

“We’ve had a brilliant six years at Twenty8Twelve and are now looking forward to new pastures,” the sisters tell WWD. “We wish the brand the best of luck for the future.” (The statement is a stark contrast to the sisters’ feelings in 2010: “These are the clothes we wear,” Savannah told WWD at the time. “And we want to keep all our girls happy.”)

Confirming the Millers’ departure, as well as the label’s plan to forge ahead, is brand managing director, Nish Soneji. “We’ve had a great partnership with the Miller sisters,” he says. The vision “will continue under the direction of the Twenty8Twelve design team.”

Check out Sienna sporting a series of Twenty8Twelve designs over the past several years (above). Tell us: Which look is your favorite?

–Justine Harman

WEIGH IN ON MORE RED CARPET LOOKS IN ‘LAST NIGHT’S LOOK: HIT OR MISS?’

She’s a California Gurl with a heart-shaped dress — and a pretty big heart, too. Katy Perry is one of many stars joining forces with eBay for eBay.com/celebrity, a new portal where memorabilia-seekers can bid on amazing experiences and items, all to support a variety of worthy causes.

Perry, one of the first to pop up on eBay.com/celebrity, is auctioning a dress worn on her California Dreams tour: a red-and-pink Swarovski-studded cotton candy pouf, which she’ll give to the winner during a backstage meet-and-greet before her Nov. 21 concert in Oakland. (At press time, bidding was up to $8,100.) VIP tickets are included, too, and proceeds benefit the American Red Cross.

Additional items available now include works of art by Jeff Bridges (up to $2,250); a meeting with Brad Pitt (currently at $10,000); and Sienna Miller‘s snakeskin boots (more affordable at $256). Proceeds from each item will benefit a myriad of charities, including Pitt’s Make It Right and Share Our Strength — No Kid Hungry, an organization selected by Bridges. Christina Aguilera and Robert Duvall are next up, with offerings coming soon.

SHOP STAR LOOKS FOR LESS

And you thought New York Fashion Week was a big deal! London Fashion Week is in full swing, and so far, the shows have impressed, offering star-studded front rows, technological advances and even a near-royal visit. Check out some of the highlights from the week’s biggest shows.

Burberry Prorsum

Promising a starry front row at London Fashion Week, the Burberry Prorsum show on Monday (above, left) did not disappoint. Sienna Miller, Kanye West and a current face of the brand, Rosie Huntington-Whiteley, sat alongside Rachel Zoe, Gemma Arterton, tennis star Andy Murray, singer Paul Weller and photographer Mario Testino at Christopher Bailey’s spring/summer 2012 show in Kensington Gardens. Tribal-inspired print dresses were paired with cropped trenches and raffia caps in a collection that put a handcrafted artisan twist on ladylike chic.

“Oh my God, that was insanity!” gushed Zoe to PEOPLE as she headed backstage. “[Bailey is] amazing. I mean, who else makes a coat like that?” she added, referring to the “reinvention” of the classic Burberry trench.

Greeting his celebrity guests backstage, Bailey got a hug from photographer pal Testino, who told PEOPLE, “I thought it was a great show — sexy sexy sexy!” As no doubt did legions of fans who caught the show via Twitter, a first for the digital-friendly brand. “This collection is all about the most detailed hand-crafted pieces and fabric innovation, creating a beautiful physical experience that is communicated digitally in dynamic and diverse ways and I love balancing those two worlds,” said Bailey.

Temperley London

Meanwhile, Temperley London (above, center) got the royal seal of approval on Monday night when Pippa Middleton showed up to support one of her favorite British designers. Wearing the “classic fan dress” from the label’s current autumn/winter collection dressed down with black suede ankle boots, the rising fashion star certainly appeared to enjoy the show as she sat with a friend, pointing out her favorite pieces from the silver-screen inspired collection, shown in the British Museum’s dramatic grand atrium. (Grace Kelly was cited as an inspiration by the designer, as was Michelle Pfeiffer’s character in Scarface.)

PA Photos/Landov

As for Pippa, she seemed to love the silky jumpsuits, kimono capes and floor-sweeping dresses adorned in beads and tassels, all of which were accessorized with über-glam head wraps. “It was really special, really amazing,” she said, congratulating designer Alice Temperley’s husband and CEO of the label, Lars von Benningsen, on her way out.

Since commissioning a bespoke emerald-green Temperley London dress for the royal wedding after-party at Buckingham Palace in April, the label has become a go-to favourite for both Pippa and her sister Catherine.

In the hot seat, next to Middleton, was actress Rosario Dawson, currently enjoying the shows in between filming her new movie in London. “I thought it was really wonderful that she came here to support Alice and it makes sense that Pippa would be here because it’s such a London staple,” she told PEOPLE post-show. So did they swap fashion tips? “She seemed lovely and I think she enjoyed the clothes as well which is always nice to see.” Excited about the ultra-feminine, oh-so-graceful show, Dawson confessed, “I loved everything, I’m salivating and trying not to drool, honestly!”

Matthew Williamson

Sunday night, Matthew Williamson (above, right presented a kaleidoscope of color at his spring/summer 2012 show. The first runway show to ever be staged in the Tate Modern’s Turbine Hall, it boasted a front row consisting of pal Sienna Miller and Rachel Zoe.

Burnt oranges and vibrant yellow took center stage, as did the designer’s signature embellishment with semi-precious stones and feather detailing. Miller, in a Williamson jacket, skinny jeans and Tabitha Simmons heels, told PEOPLE the finale number, a floor-length saffron gown with appliqué detailing and ostrich feathers, was her favorite

“The orange dress on Anja [Rubik] at the end — I love that,” she shared. With a cheer and a hug for the designer at the after-party, held on the top floor of the museum with a view of St. Paul’s Cathedral, it was a fashionable fête all around.

–Monique Jessen and Dimi Gaidatzi

CATCH UP ON EVERYTHING YOU MISSED AT NEW YORK FASHION WEEK

Want to walk a mile in Sarah Jessica Parker‘s shoes? You can (though it might hurt!). The actress, along with other stylish stars like Sienna Miller, Eva Green, Vivienne Westwood and Colin Firth, is offering up some fancy kicks for the Small Steps Project, a charity founded by former celebrity journalist Amy Hanson, Vogue U.K. reports.

The auction will kick off at the Royal Society of Medicine in London on Oct. 12; afterward, an online auction will live on eBay for 10 days. In addition to SJP and Miller, other A-listers including Helen Mirren, Kristin Davis, Helena Christensen and Rachel Weisz will be selling their soles as well. You can even score Boy George’s ponyskin desert boots from his first performance on Top Of The Pops in 1983.

The Small Steps Project raises awareness about children and families living on rubbish dumps around the world. The organization provides shoes and aid to such people, and brings attention to the cause through documentaries and other such campaigns.

Think you’re a shoe-in for a pair? Visit smallstepsproject.org to learn more.

–Kim Peiffer

JUST FOR KICKS: STARS SHOW OFF THEIR SHOES

Sienna Miller has some of the most enviable style instincts on the planet, and now one of her personal picks can be yours for only $30! The actress and designer recently lent her editor’s eye to JewelMint, Kate Bosworth‘s social shopping site which features jewelry created with her stylist, Cher Coulter. Miller is the latest celebrity to curate a bauble for the site (Rachel Bilson picked a piece in April) — and while the “Sienna” bracelet may be silver, her heart is pure gold: 50 percent of the proceeds from the piece will benefit International Medical Corps. “I’m so excited to be a part of Kate and Cher’s Curator Series for JewelMint,” Miller said in a statement. “When she asked me to curate a piece, I immediately picked this bracelet because it speaks to my personal style.” To incorporate that style into your wardrobe, visit JewelMint.com soon — it’s only on the site until Aug. 14! –Alex Apatoff

Credit: Courtesy JewelMint

VOTE: WOULD YOU WEAR THESE TRENDS?

Jason Lloyd-Evans

While New York is in full Fashion Week recovery mode, London is just heating up! Sienna Miller and her sister Savannah helped light up the British city this weekend, when they sent their fashion line, Twenty8Twelve, down the runway on Saturday during London Fashion Week. The sister act presented their spring/summer 2011 collection to a front row that included Sienna’s longtime friend and fellow designer Matthew Williamson and back-on-again love Jude Law, who explained his presence simply, telling WWD, “I’m here because I love Sienna Miller.” The collection, designed for a girl on a journey traveling everywhere from Thailand to Mexico circa 1950, took inspiration from Joni Mitchell’s “Don Juan’s Reckless Daughter” album and featured eclectic prints and pops of color, accented with delicate lace and embroidery. And while the pieces were vibrant and playful, they still managed to exude a sophisticated and luxurious look–much like Sienna herself! “These are the clothes we wear,” Savannah told WWD. “And we want to keep all our girls happy.” To check out all of Twenty8Twelve’s spring looks, visit InStyle.com. Tell us: Will you wear Sienna Miller’s latest collection for spring? –Jessie Goldberg

Chris Moore

Sisters and design partners Sienna and Savannah Miller are mixing film and fashion to show off the fall/winter 2010 collection for their Twenty8Twelve line. In a playful film directed by Angelo Pennetta, Sienna and model Sara Blomqvist play dress up with the label’s new styles on location at the Hilles–the Gloucestershire, England home of the late Isabella Blow. “We wanted to capture our new season on film to get a real feel for the collection and Hilles provided the perfect backdrop for us,” Sienna tells British Vogue. “The rich tapestries, velvets and eclectic style of the house completely reflect the elements of our autumn/winter collection. I loved filming in every room.” And Sienna and Savannah aren’t the only designers who have found inspiration at this legendary home–the late Alexander McQueen was also known to get into creative mode there. From chunky furs and skinny denim to sexy cocktail dresses and crochet sweaters, the Miller sisters are showing just how fun fashion can be this season. See more of the collection at twenty8twelve.com.–Andrea DeSimone

Nick Harvey/WireImage

That’s a bangin’ new haircut, Sienna! The British actress debuted her freshly trimmed, eyebrow-grazing fringe yesterday night at Belvedere Pink Grapefruit launch party at the Matthew Williamson boutique in London, which she attended with her equally gorgeous sister and Twenty8Twelve design partner Savannah. While the look is a departure from her signature easy waves, it’s not the first time she’s made a head-turning change–in 2005, the star chopped her long tresses into a pixie cut for her role in Factory Girl, a cut that made as many headlines as her relationship with then fiance (and now on-again boyfriend) Jude Law. Wonder what he thinks of the newest cut? Tell us: Do you like Sienna Miller’s new bangs? –David Yi

Fame; Islandpaps/Splash News Online

What do British It-girls wear to the beach? Agent Provocateur’s pin-up-girl-worthy bikini apparently, with both Kate Moss and Sienna Miller donning the gingham and denim two-piece. Moss first sported the checkered style over the summer while yachting around St. Tropez, while Miller donned the sexy-sweet set while vacationing with on-again love Jude Law over Christmas. Want to get one for yourself? Be prepared to spend some serious cash — It-girl style doesn’t come cheap, with the suit clocking in at $280, available now at agentprovocateur.com. Tell us: Who wears her bikini better: Kate Moss or Sienna Miller?

See all the beach looks we couldn’t help but love in 2009!

Danny Martindale/WireImage

It was a family affair at the Twenty8Twelve show on Monday night when Sienna and Savannah Miller’s mom, Jo Miller, step-mother Kelly Hoppen and Savannah’s husband took their front row seats at the sisters’ second London Fashion Week collection. Also in the front row — Anna Wintour and MTV presenter Alexa Chung. Backstage, the design duo confessed to PEOPLE that the collection had been hard work and was the product of much sisterly bonding and midnight texting. “We do finish each others sentences,” Savannah told PEOPLE. “Yeah, I guess we are really lucky to have a great relationship where we can work together,” agreed Sienna, as they celebrated with a much-needed cocktail. And with Sienna currently performing in Broadway’s After Miss Julie across the ocean in New York City, the close-knit sisters have proved to be as creative about keeping in touch as they were for their collection of tight denim dresses and striped leotards. “Usually I get my best ideas in the middle of the night,” said Sienna. “We text all the time and we’re always on the bbm [BlackBerry Mobile],” added her sister. With that, the actress fled the backstage area to board a plane back to New York with her mom, her dog and the memories of Anna Wintour applauding her very own fashion moment.–Monique Jessen

Peter Kramer/AP

The Devil Wears Prada and so did Anna Wintour to the premiere of “The September Issue” last night at the Museum of Modern Art in New York, but according to designers and family alike at the premiere, that’s where the similarities end. As Wintour was joined by Renee Zellweger, Sienna Miller (who appears in the documentary as the cover girl for the titular September 2007 issue), Carolina Hererra, Oscar de la Renta, Donna Karan and more fashion glitterati, friends and relatives described Wintour as anything but a Devil. “She’s an amazing mother, an absolutely incredible mother,” says Wintour’s equally-stylish daughter Bee Schaffer. “She came to all my sports games. Her kids are the most important thing to her.” But that doesn’t mean that Mom doesn’t offer unsolicited fashion advice, like what to wear on a date. “She told me to change” for a recent night out, Shaffer revealed — although she stuck to the original outfit. And Wintour doesn’t just give advice to her children. Designer Zac Posen recalls Wintour once “asked me to take a sleeve off of a dress” early in his career. “I refused,” said Posen. “And a common respect level was brought to the table. And then the dress was later shot on Debra Messing.” Designer Marc Jacobs also described a formidable Wintour with a heart. “She’s smart and she surrounds herself with the most talented people. And she’s a risk-taker unafraid of taking chances. She doesn’t suck up,” he said. “And she’s been very good to me on a personal level as well. When I was having some personal problems, Anna was always there for me. She’s really a great editor. And she’s a good mother. She’s very maternal and caring to people she cares about. Anna’s really quite a warm person, who maybe has a different reputation. But in real life she’s very warm. . . and generous.” And while director R.J. Cutler received “extensive notes,” from Wintour, the editor tells PEOPLE “He ignored every single one. It’s his movie . . . his vision.” And does Wintour, who has seen the film twice approve? “I think it’s a wonderful document, on the amazing hard work, the creativity, the talent, the heartaches and the success.” The September Issue opens in N.Y.C on August 28 and nationwide on September 11. – Jeffrey Slonim

Splash News Online(2), Startraks(2), Splash News Online

No one has ever doubted Sienna Miller‘s commitment to fashion — from cutting edge style on the red carpet to even co-designing her own Twenty8Twelve line with her sister Savannah — but she’s taken it to a whole new level this week while promoting G.I. Joe: Rise of the Cobra in N.Y.C. Yesterday, the tireless fashionista changed five times, with each outfit more glamorous than the next! Her day kicked off with a plunging red frock paired with bow-topped Chloe sandals, switching into a shimmering top and black wrap skirt from Derek Lam. Next up, a confetti print Diane von Furstenberg dress with sharp shoulders paired with two-tone T-straps. The evening saw a darkly printed minidress paired with her favorite studded black booties before changing into a casually chic black Diane von Furstenberg jumpsuit and gladiator sandals for dinner at the Waverly Inn. Phew, we’re exhausted just thinking about wearing so many gorgeous looks in one day! Tell us: Which of Sienna’s looks do you like best?

Flynet

Sparking an all-out fashion frenzy, stylish stars turned out in London last night to help designer Matthew Williamson celebrate his collaboration with H&M. The British designer, who kept pal Sienna Miller close by his side, told PEOPLE just how nervous he had been while heading to the launch of his capsule collection with the cheap-chic retailer: “In the car on the way I said to Sienna, do the heart test, feel my heart, and she did. It was pounding!” But it turns out Williamson had nothing to worry about. As VIPs like Mischa Barton and Pixie Geldof grabbed his signature vivid color pieces off the rails of the Regent Street store, he looked on with disbelief. “I was so nervous that no one was going to be here. I’m watching the rails being emptied, literally, it’s freaking me out — in a good way!” For her part, Mischa seemed to agree, congratulating the designer with a huge hug as she arrived in one of his new designs — a studded leather waistcoat and blue tulip skirt. “This is amazing,” she said pointing to a cropped leather jacket, while Sienna Miller, having completed her mission of support, sipped champagne quietly with a few friends. You can finally nab some of Williamson’s must-have looks for yourself. His collection, which ranges from $25 to $349, launchs today in H&M stores. –Reporting by Monique Jessen

Neil Rasmus/PatrickMcMullan/Sipa

She may have her own fan-base of ultra-glam celebrities, but star stylist Rachel Zoe is making no secret of her love of the “free spirit approach” of star designer Sienna Miller‘s ready-to-wear line Twenty8Twelve, created in partnership with her sister Savannah Miller. Zoe had the rare opportunity to interview the designing duo for Interview magazine — and a love of fashion, she learned, was a family affair from the start. “Our mum was very glamorous in a shimmery, ’80s sort of way,” Sienna says. “She had endless dinner parties. It was very Bohemian and inspiring to grow up around creative people in that way.” And when Savannah headed to the esteemed St. Martins design school, Sienna naturally offered input on her sister’s projects. “When we were approached to do the line,” Sienna reveals of the collection’s 2006 launch, “it felt like an organic step to take. It means we get to spend time together, and it’s a lot of fun.” And for her part, interviewer Zoe wouldn’t mind stepping into the sisters’ shoes, telling them, “It would be my dream to form a business with my sister and I envy you both for doing so.” Click here to read Zoe’s full interview with Sienna and Savannah. Then tell us: What do you think of their designs? Would you want to work with your sister?

Gareth Cattermole/Getty

While most of Hollywood was in Oscar mode, Sienna Miller and her sister Savannah were making their runway debut at London Fashion week. The designing duo behind Twenty8Twelve debuted their Fall 09 collection to a packed house which included Fashion Week staple Kanye West and fellow British designer Matthew Williamson. The clothes seem a combination of the two sisters; leather jackets, skin-tight dresses with a boho flair for Sienna mixed with crystal-embellished cashmere, fine-tailoring and florals for Savannah. “But put them together, and it says London cool,” Sienna tells the The Telegraph backstage before the show. “These clothes are funky, and there’s something for anyone.” Or, as Savannah tells Style.com the collection is “Pirates of the road meets Grace Jones.” But even with the success of the two-year old line, don’t expect Sienna to give up her day-job any time soon. “I’m not giving up acting, I love acting,” says Sienna. “But I also love working with my sister. We’ve always been two sisters playing dress-up, ever since we were kids and we’re still doing it.”

CAROLINE TOREM CRAIG/LFI

Once you have a successful film career, high-profile relationships and a successful clothing line, what’s left to do? Have a runway show, of course! Sienna Miller and sister Savannah are gearing up to show their popular fashion line Twenty8Twelve at London’s Fashion Week come Febraury. The presentation of the Fall/Winter 2009 will be the first time that the Miller sisters have taken their line of feminine dresses, tailored jackets and edgy accessories to the catwalk, and we’re already wondering what star pals we might spot in that front row! Watch out, Olsens — will Sienna and Savannah be next year’s designers of the year?

David Moir/Reuters; PA Photos /Landov

Sienna Miller and Keira Knightley are both known for their quirky British style — so what happens when you cast them both in the same film? Not only do they become close friends, but apparently they coordinate their red carpet outfits! The stars spent their day promoting The Edge of Love at the Edinburgh Film Festival. First, they hit a photocall in matching booties and black accents. But they hit the nighttime premiere in ’30s-inspired black and white — Sienna in long fringe and a bowler hat, Keira in a Chanel jumpsuit and bolero. We can’t wait to see if the actresses keep up their red carpet team effort. Tell us: What do you think of Sienna and Keira’s paired-up looks?

Jim Ruymen/UPI/Landov

Our closets are jam-packed with frocks in pretty much every color of the rainbow–but when in doubt, we always go with a little black dress. And we’re not alone in relying on the style staple. Just about every celeb in Hollywood rocks the LBD from time to time, just like Sienna Miller did in a this lace Monique Lhuillier number for the Film Independent’s Spirit Awards. Click over to our friends at FabSugar for great tips on how to choose the most flattering LBD silhouette—and learn other insider tricks for keeping the classic look fresh and fabulous.

Lawrence/Splash News online; Rasmus/PatrickMcMullan/Sipa;CAD/Fame

Scarves couldn’t be hotter for fall — and what better way to add a touch of the wild to any outfit than with a dash of leopard-print? Whether you wear it with neutrals like Keira Knightley, bold colors like Sienna Miller or with dresses like Eva Longoria, this is a can’t miss accessory! Here are a few of our favorites for you to try out. Tell us: Is this a trend you’d try?

Vote on even more star trends by clicking here!

Kashmere Camel Leopard Printed Cashmere Wrap, $135 at bluefly.com

VERA Leopard Crepe De Chine Scarf, $62 at ronherman.com

Echo Leopard Print Scarf, $38 at bloomingdales.com

Animal Multi Purpose Scarf, $9 at asos.com

Forever 21 Leopard Scarf, $7 at forever21.com

BAUER-GRIFFIN

Though we’ve seen lots of stars go dark for roles in the past few months — Jessica Biel and Mischa Barton pop to mind — we had to look twice when Sienna Miller appeared with long brunette hair on the set of her new film Hippie Hippie Shake. She was almost unrecognizable with her wig on! We definitely prefer the British star with her normal blonde bob that highlights her big blue eyes and unique fashion sense, but we want to know what you think. Tell us: Do you like Sienna with brunette hair? Or should she stick to blonde off camera?