Dress for excess: Florence Welch reveals how she’ll be rocking the Brit Awards

She has wowed the Grammys and stunned the Oscars. Ahead of Tuesday's Brits, Florence Welch tells Craig McLean why she is the go-to performer for global awards extravaganzas – and why no one wants a 'sober and boring' pop star.

Barely above freezing on a winter's morning – and as she emerges from her chaotic bedroom in the family home in Camberwell, south London, Florence Welch is dressed to impress: antique, Sunday-best dress, knee-high high-heeled boots, camera-ready make-up, ironed-flat red hair.

The 25-year-old singer's sister and sometime assistant, Grace, scuffles about the kitchen, comfily attired in sweatshirt, leggings and leg-warmers, and busy with the coffee and toast. She is 36 months her pop-star sibling's junior but, by flighty Flo's own admission, light years ahead in the grounded, practical stakes. One Welch sister is, you might say, Pre-Raphaelite; the other, post-gym. They make a great team, especially when touring.

Which is exactly what Welch has just been doing. She's fresh(ish) off a plane from Japan, where she'd journeyed from South America. Hence, she apologises, her occasional "vacant" expression and the 1,000-yard stare that speaks of mind-melting jet lag.

She'd better get used to it: Florence and the Machine's second album, Ceremonials, has been out for little over three months but has already sold 1.8 million copies around the world. There's a lot of life in it yet, and a lot of touring.

And, one suspects, a fair few awards ceremonies. On Welch's to-do list in the days after our meeting: a visit to the National Gallery in the company of BBC2's The Culture Show – with her mother Evelyn, a professor of Renaissance Studies at the University of London, Welch has a keen interest in art. And beyond that engagement, the singer has to wade into rehearsals for her appearance at Tuesday's Brit Awards.

For Florence and the Machine, it's a big do. Welch and her band are renowned for their fashionable and theatrical flair, whether in photoshoots (Welch is hot from the cover of Vogue and a Karl Lagerfeld collaboration in Paris), videos or on the television stage – they've previously wowed the watching millions with appearances on the Oscars, the Grammys, the MTV Video Music Awards and the Nobel Peace Prize in Oslo.

On top of that, the Brit Awards represent a sort of homecoming for the band that Florence and Isabella Summers (aka the Machine), a friend from Camberwell College of Arts, formed in 2007. The newbies won the event's Critics' Choice Award in 2009, and Best Album the following year for their debut, Lungs.

"It's going to be a celebration of this album," Welch says of her performance at London's O2 arena of "No Light, No Light", her punchy, dramatic, harp-flecked, aerobic-gothic new single. "And of coming back to the Brits with a record that I'm really, really proud of. We haven't really done any big UK TV stuff for this record – or anywhere for that matter. So this will be the first time we get to create something around this record. That's quite exciting. And," she dimples, "it's very nice to be invited back."

And this time, at least, she brings with her the experiences – and the fabulous frock memories – from other awards ceremonies from around the world...

The Brit Awards, London 2009

Florence and the Machine won the second-ever Critics' Choice Award. She didn't perform at the actual Brit Awards, but did at the launch event. "That gig was the first time I ever [bought] a dress for something. I've still got it – it's over here somewhere..."

Welch clatters off to her room and comes back with a mint-green brocade in sheer lace gown of 1930s vintage. It was, she recalls, like slipping on her armour for her first big TV exposure – especially useful as she was, at the time, bunkered in a London studio working on Lungs with producer Paul Epworth. She wasn't used to the spotlight.

The inaugural winner, Adele, told me she'd had to battle suspicion that the Critics' ChoiceAward had been invented just for her. "I was dead embarrassed winning that bloody award," she said to me afterwards. "What's the point of being awarded something when you ain't done anything yet?"

This year's winner, Emeli Sandé, has no such fears: she's already had a number-two single (with "Heaven") and been to number one courtesy of her guest slot on Professor Green's hit "Read All About It". And she's finished recording her debut album, Our Version of Events, released last week. ("I wanted the Brit so much," Sandé admitted to me, "more than anything. Why was it so important? Cos it's an appreciation of the music.")

Welch can't confess to such self-possession four years ago: "It was a really terrifying experience, a baptism of fire. I was completely unprepared – I was hyperventilating when I was getting the award. It was almost like having Second Album Syndrome first. I had that really intense press scrutiny, and it was my first experience of everyone really focusing on me, waiting on this record. And I still really didn't have any idea what kind of record it would be. I was still making it and figuring out the sounds.

"So it was like a lift-off, really, yet the pressure that came with that was really intense. But it has helped in the long run. It seems like I was established from the beginning."

The NME Awards, London 2009

The other end of the spectrum from the slick extravaganza that is an American awards show: a boozy, none-more-indie night at London's Brixton Academy, where pre-planned bad behaviour is de rigueur.

"I performed with Glasvegas," recalls Welch. "We sang 'Suspicious Minds', the Elvis song, together, and drank Buckfast. I got really drunk and don't remember what happened next. A very chaotic night. And a literal bunfight – there were handbags being thrown."

The Brit Awards, London 2010

One year on from her "unveiling" at the Brits, Florence Welch returned, victorious. Lungs (which to date has sold four million copies) won Best Album, and she performed on the show with Dizzee Rascal. In the glorious – and sometimes inglorious – tradition of one-off collaborations at the Brits (PJ Harvey and Björk; Estelle and the Ting Tings), they sang a mash-up, "You Got the Dirtee Love". Released as a charity single, it promptly went to number one.

Why collaborate with Dizzee Rascal?

"He was an underground artist who worked his way up to the mainstream, a self-made man. It felt like it was a really triumphant night for both of us."

As for her choice of song – based on her album's cover of the Source/Candi Staton rave classic "You've Got the Love" – she admits she was playing to the Brits TV audience at home. She wanted to "cater for a wide spectrum of musical interests". And it worked.

"Oh yeah! That was the biggest single we've had, ever! The Brits performance just took 'You've Got the Love' to another level. Dizzee and I sang it together again on the Pyramid Stage at Glastonbury – which was another moment altogether – and at Wembley for a Capital Radio event. It really took on a life of its own from the Brits."

On every level, for Florence Welch it was a brilliant surprise. "I didn't even know it was going to be released as a single."

The MTV Video Music Awards, Los Angeles 2010

"You have to not think about the millions of people who'll be watching an awards show on TV. That's the scary thing about them. Playing live feels for me very free, but when you're on TV you are within the constraints of a box – and it's preserved in that box. If you mess up it will be on YouTube forever, go round the world in seconds.

"What was really nice about the VMAs was that they allowed us to recreate the video for 'Dog Days are Over' – we were up for an award for Best Video, so they allowed us to go full throttle. That was brave of them – we were a really unknown act in America. And to give us this huge scale of a performance with all the bells and whistles – well, it could have gone one of two ways: 'Oh my God, this crazy English girl... go back home!' Or they could embrace it.

"So we arrived at the VMAs, painted 27 people blue, massive psychedelic choir, spinning podium, drummers, Busby Berkeley dancers, me in a kind of Grecian, pink extravaganza with no shoes on, lying on this podium, waiting for it all to start, looking at the ceiling thinking: [strangulated wail] 'What am I doing here?'

"And after the performance I was the most Googled person in the world for about... 10 minutes, I hope, I like to think. 'Who was that, and what was she doing?' That performance really kicked everything off for us in America.

"But afterwards it didn't really hit me what had just happened. There's always five minutes after I do an awards thing where I'm like, 'Was it OK? Did I sing? Did words come out of my mouth? Was I waving my hands?' Five minutes of denial that it went well.

"But I remember Chelsea Handler was the host that year and I passed her in the hall, and she went, 'YOU FUCKIN' RULE!' And I thought, 'Yes! Maybe it did go well.' Then I remember us all running down this corridor screaming."

The Grammys, Los Angeles 2011

This time last year, as Adele was dominating the Brits, Florence and the Machine were in America. The VMAs performance of "Dog Days are Over" rocketed their profile in the US, a process further accelerated by the song's usage in the Julia Roberts feel-good flick Eat, Pray, Love.

She was, as a consequence, very much in demand. At the beginning of February she was at the Grammys. At least, she thinks she was.

"God, I can't believe that was just last year. What's going on? Right, yes: I did an Aretha Franklin tribute with Christina Aguilera, Yolanda Adams, Martina McBride and Jennifer Hudson. There were some big voices up there – then me, English girl, at the end, looking like this..." Welch makes a lost-rabbit face.

The rehearsals, she remembers, were "really fun and relaxed". Any diva tendencies were parked at the door, although Aguilera did induce microphone envy with her custom-made jazzy red microphone stand. Hudson's cuter-than-cute infant son broke the ice by doing his Michael Jackson impersonation. Welch, meanwhile, did her best "crazy English girl" impression, dancing around backstage, much to Hudson's titillation. "There was a real warmth and it was quite celebratory. But the actual performance was really frightening – you're singing in a line in a tribute to the Queen of Soul, and you're like, 'Oh my God, my turn's coming.' I had to hold the 'Freedom!' line for about five minutes. Then Christina comes on and does her thing...

"But LL Cool J did say my name when he introduced me, which was the best thing ever."

It wasn't a performance in which she had much creative input – "I was just there to pay homage to Aretha." Apart, that is, from her costuming.

"I wore three dresses that night. That was a big evening for my outfits. An Elie Saab pink sequinned thing to the show, a Riccardo Tisci for Givenchy swan bird-like thing to the entrance. Then, to actually be at the awards ceremony, I wore a custom-made YSL lavender gown. So, a good award show for dresses. You don't get to keep most of them, though. I still have the YSL one cos it was custom-made. But the others had to go back. It is Cinderella: you do get to wear it, and love it – but for only one night."

The Oscars, Los Angeles 2011

"God, this is a rollercoaster," exhales Welch as she's reminded that she appeared at the 83rd Academy Awards two weeks after the Grammys. It was a last-minute booking: Dido, nominated in the Best Original Song category for "If I Rise", from Danny Boyle's 127 Hours, was unavailable to sing – she was pregnant and chary of the transatlantic flight.

AR Rahman, writer of the song, duly called Florence Welch. The Indian composer had seen the Titian-haired Englishwoman at the Nobel Peace Prize ceremony in Norway two months previously. "That was one of the ones I enjoyed most, actually – we got to do it with a 60-piece orchestra and a 30-odd choir. It was all acoustic, and the King and Queen of Norway were there. It was so fun to play there in that scale at an event of that calibre."

The Oscars were very different. She had to learn to sing a song where the lyrics were "emotive sounds", soundtracking as they did the moment in 127 Hours where trapped hiker Aron Ralston hallucinates and starts contemplating hacking off his arm to free himself from a boulder that had trapped him.

"The thing AR said to me was that he wanted the audience to levitate. It was to be a very serene performance, which was light years from the Grammys performance."

Lost in said serenity, Welch – accompanied on stage only by Rahman and his "electric sitar" – didn't spot any Hollywood A-listers staring in rapt attention.

"But during rehearsals they had those Guess Who?-style face cards that go on all the chairs. That was weird – Brad and Ange, Celine Dion, Justin Timberlake, Robert de Niro..."

And then to the after-party: Florence and the Machine also performed at Elton John's fabled, celeb-studded post-Oscars bash. She and Elton sang "Tiny Dancer", and he sang "You've Got the Love". "That's some big hobnobbing," she says proudly. "But we just ended up drunk backstage. We always do this, me and the band, back at the hotel room, dressing up, drunk." k

Alco-amnesia, Florence Welch cheerfully admits, is something of a theme for her at awards shows. After the Grammys, she had a "big conversation" with Win Butler, lead vocalist and songwriter of Arcade Fire, one of her musical heroes. What did they discuss? She has no idea.

"I once had a two-hour conversation with Beyoncé, apparently. And she met my sister at something and cos she's really polite, she was like, 'Grace! Hi! I've heard so much about you!' And I was like, 'Hmm... what did I say?'"

Merrily gladhanding her way round the world's premier gong-giving bashes, Florence Welch takes her Brit-muso ambassadorial role seriously. "I hope I'm not letting the side down!" she laughs. "I think I'm flying the flag. I think they'd be disappointed if a Brit was sober and boring..."

The Brit Awards, London 2012

No, Florence Welch can't tell us what she's planning for her performance in the O2 on Tuesday night. But more than likely it will be something grand. Yes, much as she loved Adele's unadorned performance of "Someone Like You" last year, that's not Welch's awards-show style.

"For me as a maximalist who's really prone to excess, that stuff is what excites me – like Lady Gaga's performances. But then you get Adele and it's that sense of being really zoomed in on someone and you're as close to them as we are now."

Mostly, she beams, she'll be there to enjoy herself. "It always feels to me that the Brits is a great British musical. It felt like that the last time we performed – everyone's running around backstage, half-dressed. Gaga's going in one room, Dizzee's in another, Lily [Allen] is coming out of that one, and there was me in some funny brocade dressing gown, barefoot, chatting to everyone. It does have that sense of a celebration. I guess I think about it in that way to help myself process it. I understand musicals."

Florence and the Machine are nominated in two categories, Best Album and Best Female. Would she like to win? She frowns and glances up at the kitchen dresser, where her Critics' Choice Brit stands next to a Q Award and some charity shop bric-a-brac ("Where's the Best Album?" she asks Grace, puzzled. "In the office," comes the reply).

"I mean, it would be nice to win," she eventually decides. "But I'm not gonna put pressure on myself to win; that would spoil it for me. I'm just really looking forward to going, enjoying being there, seeing everyone, and getting a bit drunk.

"Anyway," Florence Welch smiles, "I've got two. I don't want to be greedy."

The Brit Awards will be televised live at 8pm on Tuesday on ITV1