"It was so emotional," she bubbles, eyes widening till her eyebrow ring brushes her hairline. "First Emma started crying, then Mel C, then me, then Vicky started and we were all blubbing." She roars the full-bodied Yorkshire roar that got her christened Scary just as her phone, sitting on the table next to a mineral water, emits a ring that sounds like La Marseillaise. "What's THAT?" I ask. As she answers the call, she hoots again and says, "You think that's funny? Vicky's mobile plays Wannabe. Don't know how she did it."

Clearly, Mel B, who now answers to her married name, Melanie Gulzar, is still transported by Vicky's lavish do. Perhaps she regrets that her own wedding in September, to a Dutch dancer called Jimmy, didn't feature red velvet thrones and nude models of bride, groom and baby atop the wedding cake.

The only grandiosity about the Gulzars' ceremony, at their 16th-century Buckinghamshire manor house, was the bride's gold medieval headdress and a £1 million deal with OK! magazine. Didn't she feel that selling her wedding to a gossip mag contributed to a culture of tacky intrusiveness? "No, because if you do a deal with them, it gives you more control. They arrange security, make sure photographers aren't hiding in the bushes. I wanted pictures of my wedding, obviously, and it was the best way. There was only one photographer, and we were able to keep it private." And there the matter is closed. It was a silly question. Of course a Spice Girl would co-operate with OK! magazine. Without the media, they would still be five girls-next-door sharing bedrooms in a house in Hertfordshire.

Three years of fame have chiselled the Scary persona into something both more and less menacing. Admitting that she's "far less aggressive and brattish" these days, mainly due to the arrival of four-month-old Phoenix Chi, she's also less jolly. She dons a second skin for interviews, impervious to attempts to win her over. Saying that, she's perfectly friendly as she settles down to discuss her new solo single, a cover of Cameo's funk classic Word Up which she recorded last spring with hip-hop producer Timbaland.

Once you suspend your disbelief about a Spice Girl uttering the words "Sucker DJs who think they're fly", it's not bad at all. "I can't compete with R&B singers, 'cos they have voices to die for, but I can sing!" she says, with some surprise. "I was so shivery when I heard my voice played back." It's her second venture after last year's chart-topping duet with Missy Elliott, I Want You Back - and the first Spice-made record to chart outside the top three. Word Up debuted at a humbling 14 this week; radio has been slow to take to it, though it's more listenable than a good few Spice singles.

"I'm really pleased at getting in at 14," she maintains, all professional stiff upper lip. "I knew it wasn't as radio-friendly as the first one, and I was just crossing my fingers for the top 20. It's not all about number ones." She pauses to nibble a sleek forefinger, treating the waitress, who is setting down another mineral water, to an eyeful of jewellery. There's a wide diamond engagement ring, a silver ring with three gems representing "me, Jim and Phoenix", and, most arrestingly, a gold watch with a dial encircled by heavy-duty ice. The rocks must be worth £25,000, but she wears them as casually as you do when you're 24 and famous beyond imagining.

Melanie arranges her floral-trousered legs into the lotus position and rakes her fingers through her mad curls. Physically, she does a great impression of Scary. At one point, she laughs loudly enough to reveal the famous tongue stud. Yet the Spice characterisation conceals - in Scary's case, at least - an introspective nature. "When I wrote the songs for my album, I dived into my diaries, which I've kept since I was young. I write every day, even if only to say, 'This has been a crap day', and it's my own therapy. I get out all my negativity. I write poems, too. It's like a reality check." What sort of negativity? "You have your days," she replies evasively. "It can just be PMT, or whatever."

If the negativity has its roots in her mixed-race childhood in Leeds ("I'm not black, I'm mixed-race," she sternly asserts), she isn't saying. Her solo work seems to address the black half never given full rein on Spice records. She grew up listening to her Jamaican father's R&B records, and her teenage favourites were Neneh Cherry and Maxi Priest. "I used to hate pop, because it was all Pete Waterman and Jason Donovan." She grimaces delicately. "When the Spices get together, we turn out happy pop music, which I love, but I've been wanting to do something like this for a long time."

She speaks excitedly of her forthcoming collaboration with Gangsta Spice Snoop Dogg and of a session with swingbeat maestro Teddy Riley, who "kept me in the vocal booth for 13 hours with no break". Her thrill at paying her dues suggests that musical respect might be what she has wanted all along. Respect alone wouldn't have made her monstrously famous, however, and Melanie shows no sign of boredom with her day job. She doesn't even regret the product endorsements (remember the pink Spicecams?) that cost them credibility. "We did five and thought, 'Why not? If it doesn't sell, it was a bad idea and we won't do it again.' But I suppose if I could go back, I wouldn't do so many."

This appears to contradict the rumour that tie-ins were behind the sacking of Spice manager Simon Fuller. A clause in his £15m pay-off prevents either side from revealing the real reason; all Melanie will say is that he left "more for personal reasons". Maybe Fuller, like Sporty, snored. Melanie relates a tale of their early days, when the two Mels shared a room in Finchley, north London. "And she snored. My God. At one point we shared a bed, and I used to have to wake her up. But I felt guilty, because she was so heavily asleep." Mel G is at her most charming reminiscing about their pre-success slog, which formed such close bonds that, she says, she'll never leave the group. She's less forthcoming on more topical questions, which these days number just two: did she force Geri Halliwell out? And (as the tabloids are frothing to know) are she and Gulzar divorcing? "No" to both, apparently.

"Me and Geri have a love-hate relationship," Mel explains, not really explaining anything. "She sent flowers for my birthday, we've talked on the phone." Why wasn't she invited to your wedding? "Because I hadn't seen her face to face since she left, and you don't want to see someone for the first time at a wedding. I'd rather meet in private first, but that'll come. I think her album is good, for what she's doing." She pauses, then opts for honesty. "But it's not my kind of music. I don't really feel anything for it." Insiders suggest that the pair, big personalities both, were the band's decision-makers, and in the end one simply had to go. As for her marriage - she says it's sound.

The real question is whether the Spice Girls can reclaim their position when they return from their year off in August. Girl Power has entered the lexicon, but pop has moved on, and Mel isn't sure where they'll fit in. "We'll know when we get together. There's always a vibe when we meet. We'll instinctively know what we're going to do next." And there's always the solo career...