miller's tale; With her jaw-dropping beauty, heart-throbbing fiance, and showstopping style, Sienna Miller is the girl of the moment.(Biography)

Byline: Hamish Bowles

On Christmas Day 2004, Jude Law proposed to Sienna Miller, confirming her status as Girl of the Year. This golden sprite, a tender 23, is on the cusp of an intriguing movie career of her own; she is also possessed of an idiosyncratic and influential instinct for fashion. Even on a glacial London day in Notting Hill, she exudes an air of street-wise fashion authority, bundled up against the cold in a black denim kilt and a studded leather belt-both eighties-with a short black felt cape, thick ivory knitted scarf, Venetian fisherman's hat, battered and beloved cowboy boots, and black tights. She later realizes that these tights are peppered with holes, for although Miller was born in Manhattan (her father, Ed, is an American banker) her style is quintessentially devil-may-care English. "She has this great energy and joie de vivre," says her friend stylist Bay Garnett, "and spirit is style-that's why things look so good on her."

Miller delights in breaking rules. She will wear a skirt as a minidress, cinching it across the bosom with a great vintage belt. She will push the wrist-size bangles she adores above her flamingo-knuckle elbows. Over layered T-shirt dresses she will shrug on an old white mink jacket belonging to her mother, Jo, an entrepreneurial blonde beauty, hippie fashion plate, sometime model, and yoga-school founder who has inspired her daughter with a passion for the sixties, seventies, and eighties. "She had beautiful clothes-Ossie Clark and Biba and old Birkin bags," says Miller, sighing, "but she gave absolutely everything away. She kicks herself for it!"

Miller's shopping tastes seem an attempt to re-create that long-vanished wardrobe. She has shopped vintage in New York, Los Angeles, even Colorado (when visiting family)-as well as London's Portobello Road. "I suppose I do like quite bohemian-looking clothes," she admits, "and vintage is just cut so much better."

At One of a Kind, she admires the smocking on a forties frock and the spiraling seams on a Vivienne Westwood knit dress. At Rellik, the holy grail for London girls like Kate Moss and Naomi Campbell, she falls for a prim Jean Muir dress with a whiff of Baroness Thatcher in the neat bow tied at the neck. "Very New York Chic Girl!" says co-owner Steven Philip in his wry Glaswegian drawl. Miller tries it on but instinctively unties that bow, unbuttons the front, and yanks it off the shoulders, transforming it completely. Suddenly it's Very London Hip Girl-a sexy, ironically elegant dress.

It may be her liaison with Law that has made her a tabloid star and exponentially raised her profile (Law moved in with Miller shortly after his divorce from actress Sadie Frost, the mother of his three children), but it is this intuitive sense of style that has captured a moment and excited the fashion world. Miller's improvisational looks-her fur gilets, miniskirts worn with Ugg boots, and taste for airy vintage-y chiffons with cowboy boots-have already filtered down to the high street. It's official: Miller has joined the historic pantheon of "It girls," from Clara Bow to Kate Moss by way of pneumatic starlets and fractured socialites, like the lovely, doomed Edie Sedgwick-whom Sienna Miller, in an inspired piece of casting, is set to personify in George Hickenlooper's upcoming independent movie Factory Girl.

After attending an establishment English girls' boarding school, Miller left for New York to pursue her passion for acting at Lee Strasberg. Here, she promptly dyed her hair pink and went "a bit nuts!" with her clothes. She also took time off for some modeling assignments. Bruce Weber's photographs of her taken ...