Florence Welch, the titian-tressed lead singer of Florence and the Machine, has become an idol of the frenetic indie set. But when she received word in December of her first Grammy nomination, for best new artist, she was lounging around her parents’ London home in classic languorous-bombshell mode.

“I was wearing this amazing vintage bright pink Christian Lacroix dressing gown, which was kind of ideal to receive news like that,” Welch said in a recent phone interview. “It has these incredible shoulder pads, and I sometimes wear it with this feather headdress — it’s like the cowboys and Indians flimsy kind — that my sister made. It makes me feel like I’m in ‘Gone with the Wind.’ ”

Welch, who is 24, almost 6 feet tall and model-lanky, has emerged as a refreshing new fashion muse on the music scene. Unlike so many of her young contemporaries (Lady Gaga, Katy Perry), who are groomed so glossily that they could double as Comic-Con characters, Welch wears her hair disheveled and favors loose peasant blouses and billowing cape-sleeved dresses.

From thrift stores …

“I’ve always been attracted to romantic, secondhand clothes,” said Welch, who has a strong jaw line, long nose and gray-green eyes that turn down at the corners. “But my style developed as I started going to these strange raves where everybody had these very definitive costumes.”

Welch was raised in London and developed her bohemian style playing dress-up and “fishing around in secondhand stores.” She and her school friends would pool their lunch money and use it in turns on thrift-store shopping sprees.

“I like the idea of taking off like a bird,” she said of the cape sleeves that are part of her signature look. During a performance of her uplifting single “Dog Days are Over” at Don Hill’s in West SoHo, Welch worked with the exaggerated silhouette by lifting and twirling her arms in hippie-child ecstasy. “It’s this romantic idea that the music could literally lift me off the stage,” she said.

Fashion companies have been quick to capitalize on this gypsy-like allure. Shortly before the 2009 release of Florence and the Machine’s debut album, “Lungs,” the fast-fashion retailer Topshop approached Welch about designing her stage attire for the Glastonbury Festival that year. “She’s a born showgirl,” said Topshop’s head designer, Jacqui Markham, who collaborated with Welch on three costumes, including a bodysuit with dramatically fringed neckline and sleeves. “She has a natural playfulness and innate quirkiness about her.”

… to high fashion

Noticeably, since the album became a hit, Welch’s wardrobe has accelerated to considerably more luxurious looks, including the Roksanda Ilincic asymmetrical black silk gown with lace detailing she wore to the 2010 Brit Awards last February; a peekaboo Chanel black chiffon dress with embellished panels at the 2010 V Festival in August; and a gold floor-length gown with leaf embroidery, by Elie Saab, at the Sundance Film Festival in January. Then there was the stunning long-sleeved Givenchy fall 2010 couture gold lace gown she donned for the 2010 MTV Video Music Awards, which some online commenters deemed too sophisticated for the event.

“Well, I suppose it’s a compliment in a way,” Welch said of the reaction. “Look, if Givenchy is going to lend you a dress, I’m not going to turn it down. I would wear that dress to just go out and buy a pint of milk if they would lend it to me.”

Since 2009, Welch has been working with the London-based stylist Aldene Johnson, who is also the fashion editor of Vice magazine in Britain.

“The process of working with Flo has evolved,” Johnson said in a phone interview. Welch, whom she described as “quite brave, quite up for trying things,” is her first and only celebrity client. “The bigger she’s gotten, the more we can do different things than what we could do in the beginning.”

On the runway

As tends to happen with musicians of the moment, Welch’s sensibility has also seeped onto runways. Both Valentino and Dries Van Noten used Florence and the Machine tracks for their spring 2011 shows. Mulberry went even further, hiring Welch to sing at its after-party and putting a parade of models in red wigs on the catwalk, though fortuitous timing also played a part.

“It was a perfect colliding of inspirations,” said Emma Hill, Mulberry’s designer. “I like to design with one girl in mind to have a consistency to the collection, and we found this gorgeous girl from Finland, Julia Johansen, who opened our show. Coincidentally, she has red hair like Florence, and we liked the idea that all the other girls would be mirror images of Julia with red wigs and all. It was all quite bizarre.”

Welch watched the spectacle from the front row, wearing a sheer black blouse from her own closet with a Mulberry skirt and booties. “As all the models were filing out, my friend, who was sitting opposite me, was laughing,” she said. “She was like: ‘You should be walking off the runway, too. Go join your fellow girls in the land of ginger.’”