Florence and the Machine: Meet the sound of the summer

Even with a loo roll stuffed down the back of her frock, Florence Welch – aka Florence and the Machine – is a commanding presence. In towering heels (which look great when she's standing still but perilous when she tries to walk) and a taut, shimmering dress (made tauter by the loo roll, which is the whole idea), her piercing eyes peering from beneath the fringe of her flame-red hair, she turns sharply to the photographer, who's just asked her to sit in a cheap office chair. "An office chair? Are you sure?" He's sure. He's obviously got a vision, but I'm no more convinced than she is, and her stylist is incredulous. So she sits in it – she's a polite girl, after all – but she doesn't like it.

What Florence knows, and I know, and her stylist knows, is that office furniture doesn't mix with her pop-star persona: one-part vengeful woodland spirit, one-part pre-Raphaelite damsel, no-part saucy secretary. Yet the first time I saw her in a newspaper, back in 2007 – the first press she'd ever done – she was looking coy in her dad's stripy shirt and a pair of brogues, a chummy, workaday sort of gal. "I was so embarrassed about that picture," she says now. "I looked really gawky, and I felt vulnerable because I hadn't decided what sort of music I wanted to make, and I want to dress to suit the mood of the music."

It's quite a transformation she's undergone, even since her first single (from June 2008), the punky "Kiss with a Fist", the video for which involved her bopping around a blank studio in a miniskirt, looking for all the world like the next Kate Nash. Which would be fine – there's nowt wrong with Kate Nash. Except that Lungs, the debut album Florence has recorded with her seven-man band, sounds a lot more like Kate Bush: dramatic, sensual, and a little scary. Oh, and brilliant, too.

"It's a kind of protection. I didn't construct the image deliberately, but as the music got more overpowering I felt I needed to compete with it. I wanted something that would put me in a more dramatic place, and it just happened as I toured; all my inhibitions about what to wear went out the window – which is how I ended up onstage at Reading in a lime-green catsuit, wrapped in a curtain."

fter the shoot, having changed into a low-key boho outfit and some more practical battered- leather boots, Florence sits outside a pub in London Fields, forking a jar of cockles. "I love weird food," she says, grinning and prodding the air with one of the slimy grey shellfish. "I discovered Wasabi peas long before any gastropub ever did." An honest-to-God foodie, she idolises restaurant critics, and raves excitedly about spotting a well-known reviewer at her favourite tapas place.

Despite the forest-faerie act, the 22-year-old is an urbane south Londoner, born and bred. Her father Nick is in advertising, and reportedly coined the Aero tagline "Have you felt the bubbles melt?" for Saatchi and Saatchi. Her mother Evelyn, once a Studio 54 regular and acquaintance of Andy Warhol's, is a professor of art history, specialising in the Italian Renaissance. Presumably she's named after the Tuscan capital, then? "I wish I was. I travelled there lots as a kid," Florence recalls wistfully. "But I'm actually named after a great aunt, which is a lot less romantic."

Her parents sound a glitzy pair. "I saw my father as glamorous," she says. "I was always trying to impress him. But it's my mum who had the really rock'n'roll life, and she's really down to earth and academic." They separated when Florence was 13, at which point Evelyn moved in with the next-door neighbour and his children. The arrangement took some getting used to.

"When you're growing up, everything's very cut and dried, right and wrong. But as you get older, you make mistakes yourself and learn to be less morally proscriptive. I'm very non-judgemental when it comes to relationships now."

Florence and the Machine's live performances are famed for their dynamism and abandon but, as a child, she claims, she wasn't much of a performer, though she did demand singing lessons when she was 11. "I was a shy kid," she insists. "I wasn't the one to jump up at Christmas dinner and say, 'Look at me!'"

She may have been shy (though she has a tendency to burst into song at every opportunity), but Florence was still a rebel, after a fashion. She was almost sent home from school when she dyed her hair red. During a teenage punk-goth phase, she started a band, The Toxic Cockroaches. "It was just a drummer and me singing, which is weird, because that's what Florence and the Machine started as, just me banging drums and singing."

At Camberwell College of Arts, where she took a year-long foundation course, she displayed a fondness for the confrontational. One of her pieces comprised the words "You're a Twat" rendered in six-foot-high letters. "I like statements and signs," she explains. "I like Tracey Emin and Ed Ruscha and David Shrigley. But lots of the signs you see on the street every day are bizarre. One of the songs I wrote was called 'Are You Hurting the One You Love?'. I just saw that printed on a bright pink sign attached to a church, and thought, 'What a fucking question!' But yes, probably. Isn't everyone?"

She maintains, however, that she's not really the confrontational type. "I tend to shy away from conflict. But everyone has a flipside. Mine comes out when I've had too many vodka tonics. Then I have a tendency to throw myself into harm's way. I'm ruled entirely by my emotions in life, but on stage I can channel them into each song."

Spontaneity has served Florence well. In 2006, she drunkenly cornered Mairead Nash, one half of DJ/ promoters Queens of Noize, in the loo at a club night. She sang at her and, instead of calling security, Nash agreed to be her manager. While in the early stages of recording Lungs, she found herself rehearsing next door to James Ford, the Mercury Prize-prone producer of Klaxons and Arctic Monkeys. She knocked on his door, gave him a CD and – hey presto – he asked to work with her.

For someone whose path to success is characterised by such single-mindedness, she's always been rather distractable, or so she says: "I find it hard to stick to goals, so it's nice to have something to focus on now; I could still be bumbling along at art college, had I not taken those chances."

Even now, Florence's guitar and piano playing extend little further than bashing the odd chord, yet she wrote her first song aged 13. "My first songs were about imaginary break-ups. I'd never even had a boyfriend and it was all very flowery and poetic, like [sings sweetly] 'And the tears from the trees/ Fall like raindrops/ On my pain" or [rawer, punkier now] 'There's a rose on the table/ It's the last thing you gave me/ And it's DEAD!' I guess I'm still melodramatic, but now it's about real experiences."

Most of Lungs was written while she was in the throes of a nasty break-up – the first time that her heart had ever been broken: "It was a relief. I thought, 'I've always had it coming, but now I know it will never be this bad again.' It was a sad, manic time, but that sense of complete abandonment was intoxicating, too, like riding your bicycle too fast with your eyes closed."

Though emphatically not a song about domestic violence – contrary to the complaints of some radio listeners – "Kiss with a Fist" features a feuding couple smashing plates over each other's heads and setting fire to the bed ("It's just a silly rhyme I thought up when I was 18!"). In "Girl with One Eye", Florence threatens to cut someone's heart out because they made her cry. Bit of an overreaction, no? "I've always been attracted to dark imagery. I used to believe in vampires and werewolves. I get night terrors, panic attacks. Even as a kid, I'd be more inclined to write about a flower dying than blossoming."

There's a literary bent to her lyrics, too, which are packed with references to the likes of King Midas and Alice in Wonderland. "Dog Days Are Over", the catchy album opener, was inspired by a giant text installation (of the same name) by artist Ugo Rondinone. Flo's current reading list is extensive and predictably morbid: Cormac McCarthy's The Road, White Noise by Don DeLillo, the plays of Samuel Beckett, the collected poems of Sylvia Plath.

"Dog Days Are Over" ought to be the album's highlight, but it's got stiff competition. The new single "Rabbit Heart" features Florence's signature panoramic vocal – powerful, enthralling and overdubbed with so many harmonies she sounds like a massed choir of one. "The guy who mixed it nearly had a nervous breakdown," she confesses sheepishly. Largely recorded in a disused synagogue, Lungs was produced by Ford, Steve Mackey (formerly of Pulp) and Paul Epworth, who has helmed for Bloc Party and Kate Nash. It traverses varied terrain, from the lo-fi punk of "Girl with One Eye" to the debonair pop of "Hurricane Drunk" via the astrological mini-epic "Cosmic Love".

As long ago as December, Florence and the Machine was named winner of the Critics' Choice award at the Brits. That's the gong that Adele won last year, before selling over a million records and taking home a brace of Grammys. Music Week has already called Lungs its album of the year, with a full six months of the year to go.

Since the record's completion, Florence is back in love with the same chap, "but it's difficult, because half the album is about breaking up with him! 'Drumming' [another Lungs track] is about seeing your ex and it feeling like something is physically attacking you. We listen to it now and I'm like, 'Erm ... Sorry about that.'" 'Lungs' is released on Island Records on 6 July