Last laugh for Billie Piper

Billie Piper has been up since 6.30am, but she looks rested and relaxed sitting on the bare floorboards of the studio in the East End where our photo shoot is happening.

She chose to get up early so that she could stay with her husband, Chris Evans, at their Lutyens-style house, Hascombe Court near Godalming, Surrey, rather than their Knightsbridge flat. She's off to New York tomorrow.

'I'm going with the girls,' she says, 'and I'm taking all those outfits that I'm too scared to wear in England, like tutus and pink tights. And I've got a new hairdo,' she adds, running her fingers through a thick brown fringe and blonde bob - inspired, she tells me, by Sophie Dahl's new hair.

'I'm so excited because when I last went I was only 17 and wasn't old enough to party. This time I can really experience the club scene.'

Unbelievably for someone who's been around for so long, Billie has only just turned 21.

The eldest of four children (she has a brother, Charlie, 14, and two sisters, Harley, 12, and Ellie, ten), she was a provincial girl with big ideas.

She persuaded her builder father and housewife mother to send her to Sylvia Young Theatre School in London (alumni include Victoria Beckham and Emma Bunton).

'I was so ambitious,' she says with a grin. 'I don't know where it came from, except that I didn't want to stay trapped in Swindon.' Billie set about planning her escape very early.

'I went to my parents with a list of the reasons why I wanted to go to stage school and said, "This is what I want to do with my life." ' She was just 12.

While she was at Sylvia Young's, Billie was spotted by Hugh Goldsmith, managing director of Innocent Records, who was looking for a singer to take on the Spice Girls.

He's said: 'Her vocals were absolutely beautiful. She had a great tone - she sounds a little black - and soul.' At the age of 14, Billie signed a three-album deal.

At 15, she had a number-one hit with 'Because We Want To'. Two more number ones followed and an album, Honey to the B, went double platinum, selling half a million copies in the UK alone.

Then things started to go horribly wrong. An intense year-long relationship with Ritchie Neville from the boy band 5ive faltered. Then she went on TFI Friday and met Chris Evans.

Neville began drinking and brawling in bars, blaming his sadness on the end of the relationship. Meanwhile, Billie was out partying frenetically at Sugar Reef, St Martins Lane and Bar 38, where she eventually collapsed with 'exhaustion and a kidney infection' and ended up in hospital.

Death threats from a deranged fan, Juliet Peters, who wrote letters to Billie declaring that she wanted to chop her head off, ended up with Billie sobbing in court while giving evidence.

Billie's PR company dropped her because of Chris's interference with her image, Virgin dithered about releasing a new single and Billie's manager, Nikki Chapman, the Pop Idol judge, cancelled their three-year contract.

It was Evans, now 37, who saved her. The ginger-haired bad boy of Virgin Radio, TFI Friday and The Big Breakfast, a divorcé with a child, was an unexpected knight errant.

After their first meeting he sent Billie a Ferrari filled with red roses, ignoring the fact she couldn't drive. Despite the 16-year age gap, the relationship has been a success.

Certainly, her mother thinks so: 'All I know is that Billie wasn't happy for quite a long time and now she definitely is,' she has said.

With £50 million in the bank, Evans whisked Billie off to LA and married her six months later in the Little Church of the West in Las Vegas.

Billie wore flipflops and a stubbly Danny Baker was best man. They took the second most expensive wedding package the chapel offers, dispensed with rings and wandered back to their hotel, Chris swigging champagne out of the bottle.

The couple took two years out and seemed to be on an endless bender. But Billie paints a different picture: 'I didn't want to sing any more, Chris wanted to write and LA was the perfect place to get away from everything.

'We hung out, played volleyball at the beach and went to restaurants. The drinking was never an issue.

'I never thought, "Oh my God, my man has a problem." My friends go to university and drink solidly for three years. We weren't doing anything that other people don't do apart from having some time off.'

It was this extended honeymoon that Billie believes made her relationship with Chris a success.

'So many relationships don't work out because couples don't have time together at the beginning,' she says in a voice which still has the occasional West Country intonation.

'It feels like we've been mates forever and I much prefer that to the temporary feeling, when you like someone but you don't know if they're going to be there when you get home. I like feeling settled at home.'

Billie and Chris have proved the middle-class doubters wrong. Billie paints a picture of marital bliss: of Sunday roasts ('Chris is an excellent cook'), walks in the country with their dogs, trips to Borough Market. And a moderate relationship with alcohol.

'We don't drink every night,' she says firmly. 'The weeks are for work, staying in and watching films, and the weekends are for going mad.' Which means nights out at Pucci Pizza on the King's Road or Sketch.'

Billie's fluctuating weight has been much scrutinised. Every now and then she and Chris check into a health farm for a three-week detox and then they're back to hearty meals and piling on the pounds.

But headlines such as 'Desperate Billie Pops Slim Pills' or 'A Bigger Billie' haven't bothered her.

'We don't read the papers, but my mum was upset by the reports,' she says. 'I was going through a bit of a rebellious stage, because ever since I left school I was preened and groomed.

'But maybe I'm not designed to be stick-thin and wear tiny skirts and platform shoes.'

Clearly her husband doesn't mind what she wears or weighs: 'Chris doesn't give a shit. There's nothing sexier than people who are confident or happy in their own skin. I hate men who are worried about appearance. It's so ugly.'

Today, Billie looks as though she's stepped out of a Gap ad. She's a trim and healthy-looking 5ft 5in in jeans, trainers and a red Fair Isle jumper.

'It's my Christmas jumper,' she says. 'Chris has one, too. He wore it when we had our first proper kiss.'

The thought of a grown man in a cosy jumper kissing a child may seem slightly disturbing, but Billie is clearly so in love and talks about Chris with such enthusiasm, you can't help but shunt the puritanical thoughts aside and join her on her perky ride.

Her on-screen clinches have included Dennis Waterman, the ageing ex-Minder actor, and James Nesbitt from Cold Feet. For although she began her career as a singer, Billie is now an actress.

'I can't see myself singing ever again,' she says, adding, 'There's not one thing I miss about the pop world.

'When Innocent Records found me at drama school, I told them I wanted to be an actress but that singing seemed exciting and I hoped it would open doors for me.'

Which it certainly has: since September last year, Billie's been busy filming. She played Angel, Orlando Bloom's love interest in The Calcium Kid, an indie film which will be released later this year.

'Orlando's a really sweet guy,' she says. 'He plays a milkman boxer and I play this dolly bird who walks around the ring in shiny swimsuits.'

Then there was her role in the critically acclaimed The Miller's Tale alongside Waterman and Nesbitt, the first of the BBC's modern adaptations of The Canterbury Tales.

'You don't realise the responsibility until you're on set, surrounded by crew and everyone's waiting for you to say a line,' she says of the experience.

Nevertheless, she was a sensation in the role: critics said her performance was 'genius', that she was 'funny and heartbreaking at the same time'.

Following that success was a film with Dougray Scott, Emilia Fox and Jimi Mistry, called You Don't Have To Say You Love Me, in which Billie plays an art student.

'I had to do a bit of girl-on-girl with a beautiful actress called Keira Malik,' she says. 'It was weird kissing somebody with soft lips and no stubble.'

Evans was sanguine about this: 'I told him the night before and he just laughed.'

She's just finished filming her most challenging role to date, as a teenager with a troubled background in next year's BBC special on children in care.

Despite the years off, Billie is highly ambitious. As a teenage pop star she used to stay awake worrying about work; now she says: 'I don't bite my nails or smoke unless I'm working.

'I put pressure on myself and make it more panicky than it should be.'

When she's not got a role to prepare for, Billie spends her time reading biographies of actors and watching old movies for tips.

With this string of acting roles, it appears that Billie's star is on the ascendant while Chris's is on the wane, particularly after two TV series (Channel 4's Boys and Girls and Live with Christian O'Connell on Five) were dropped because of poor ratings, but Billie defends him.

'He has a new production company, a show running called Terry and Gaby and he's writing. Because he's not in front of the camera, so much of his work goes unnoticed.'

Nevertheless, Chris has had a difficult time lately. In August 2002, his best friend James Ward, landlord of his local pub, drowned while on a sailing trip with Chris and some friends.

This summer Evans lost an unfair dismissal case against Virgin Radio (he'd walked out amid a flurry of sick notes and beer cans) and had to pay £7 million compensation to its owners, Scottish Media Group.

But Billie insists that she doesn't get involved in the business side of her husband's career.

'I don't want Chris to come home and have to explain to me what he's been explaining in court for however many hours. If he came home and I said, "Oh my God, I'm so sorry about your loss," ' she says in a mock dramatic voice. 'He'd be like, "Put the kettle on."

'You have to make a conscious effort to switch off because it's just not important. If I let him think that all that stress and money was important - you know, that kind of stuff can kill people.'

They can, she claims, get by without the luxury they live in at present. 'We're both from families that have nothing,' she says. 'We could survive again with nothing but it probably wouldn't be as much fun.'

Billie tells me she's thinking of renewing her vows with Chris, maybe next summer, and I wonder if she's also thinking about babies.

'I go through phases of wanting a child,' she admits, but lacks experience with them.

'In the BBC film I had to hold this six-month-old baby and I was really crap at it. I got panicky thinking, "My God, I'm never going to be able to hold a baby."

The director said, "We're going to have do that scene again, Billie, because you look so awkward." '

I imagine that awkwardness will fade. Right now, Billie and Chris present a surprising but convincing picture of domestic bliss, Evans-style.