How absolutely fabulous it is to be a Spice Girl. To wear the Spice Girl ring from Tiffany's ('It was Geri's idea: they've got "Spice" engraved on one side and "One of Five" on the other')! To be globally acclaimed in your 20s (Brit Awards)! To be rich (£80,000 a week) and famous (tabloid column inches day after day)! To be a role model (Girl Power), and a representative of your generation (Youth Vote)! If you're a Spice Girl, princes dote on you. Politicians fawn on you. Paparazzi depend on you. Primary schoolchildren want to be you.

And of the five little Spice Girls, how even more absolutely fabulous to be Victoria Adams: numero uno in the Spice Girl popularity polls. She has the best nickname (Posh), the best car (Mercedes SLK) and the best boyfriend (David Beckham), from the best team (Manchester United). Becks is a joy to behold as he displays the best right foot in the Premier League, not to mention all his other physical attributes, plus he doesn't kiss and tell, plus he buys her fabulous presents from the best shops (a silver and gold Catier Tank watch to match his own).

Other Spice Girls have problems, worrying little niggles which they have to circumvent or rise above. Victoria doesn't. She doesn't have a past, like Ginger Spice, so there are no nude pictures popping up. She doesn't have a horrible tongue screw clanking around her mouth, like Scary. She doesn't have 'the bum of a 41-year-old' (Daily Mail), like Baby, or a wardrobe full of dreary nylon trackie bottoms with Adidas written all over them, like Sporty. She doesn't - it's true - have the dazzling smile displayed by all the other Spice Girls, which shows off their brilliant white teeth and faultless orthodontics, but what the hell? Victoria's learned to pout for her publicity pictures like a moody supermodel, smouldering away with mouth closed.

Anyway, smiling or unsmiling, Posh Spice has all the best clothes. 'Prada and Gucci! Prada and Gucci!' she says, as though they were joined at the hip like Dolce & Gabbana. She's leaning back on the sofa in the Abbey Road studios, looking utterly sweet and half-naked after the prevailing fashion this summer, in a black jacket (Gucci), a red microslip (high street: 'I wanted a nightie dress'), no bra and a G-string ('I always wear G-strings'). She wears very heavy make-up for a girl in her 20s, right down to the brown cheek contouring and bronzing powder.

She did a fashion flounce for me, removing her stiletto (patent pewter Gucci with steel spikes for heels) and raising her foot waist-high, so I could check out her painted toenails. 'Black's the colour, dahling!' As she was being fitted into couture gowns at the Ritz in Paris, Tatler's stylists had told her nail polish 'must be black, silver, gold or blood-red). Her toenails were none of these. 'Ooh, I'm breaking the Tatler rule today. This is a very, very dark brown. But you can say it was black.'

Karl's people had organised a seat for her at the Chanel couture show. 'It was right in the front row, and it had a little gold thing on it saying "Posh"!' she said, eyes sparkling. She'd been dying to sit in it, on client side, among the ageing millionaires' widows with their taut skin and hard eyes. Young clients are a rarity in couture: especially young clients with enough purchasing power of their own to buy the hand-built couture artworks at £30,000 a pop. But alas, she didn't make the show. Didn't have the time. Eight hours in the Ritz being fitted into John Galliano's Dior corsets and Lacroix's sumptuous gowns eats into your busy Spice Girl life. She was amazed by the corsets and awed by the runway models' resilience and professionalism. So much underpinning, so many layers. 'I felt about 50 stone with all them layers on,' she said, spraying around her Hertfordshire vowels and her north London syntax with feeling.

Let's get this Posh thing out of the way, shall we? Victoria Adams may well be 'posh' so far as the tabloids are concerned (big house in Cheshunt, swimming-pool, Dad did the school run in his Roller, siblings are equally smartly named Louise and Christian), but her speech rhythms are not what you'd call Sloaney. A few examples. Victoria on the Spice Girl chemistry: 'It's a vibe thing. When we get in the studio we all vibe off each other.' Victoria on the media: 'I never read that piece in The Spectator. I don't ready hardly anything.' Victoria on the Prince of Wales: 'When we met Charles we was all really, like, cheeky with him. And at the end of the day, prince or no prince, he really does sit on the toilet like everybody else. You just got to picture him with nothing on.'

She rolls her eyes. 'Everybody meets me and they say, "Why are you called Posh Spice?" And I say, "Listen, I don't speak that badly! It's only 'cos I'm tired, for a start"' She was brought up in Hertfordshire by her parents, Jackie and Tony. Her dad runs an electrical distribution company (Distributing what? 'Oh, all sorts of electrical bits. Lightbulbs. Computers. All over the world'). He bought his Rolls-Royce once he made his money and famously took Victoria to school in it, though she begged him to take her in the van instead (He just said, "Oh, get in the car." Now of course, I'd want him to take me right up to the front door').

She was picked on at her local school, and not just because of the Roller. She was well-behaved and smartly turned-out by an affectionate and aspirational mother who arranged after-school Brownies and ballet classes for Victoria to shine in. 'I used to get on with my work. I used to be at school on time. I wasn't round the back of the school sheds having a fag or drinking or having loads of boyfriends - I didn't even have a boyfriend then. I was really well-behaved and that isn't the cool thing to be. I was totally straight.'

In so far as she has a home at all - apart from the first-class hotels and rented Spice Girls houses and the looming possibility of overseas tax shelters - it's still in Cheshunt among her tightly-knit family ('My sister's best friend, and my brother is too'). Her mum keeps her vast scrapbooks and deals with fans. 'My mum said, "I've given you a nice name and I don't want it shortened", and I think you take over your parents' values, don't you? Even the way they vote [Conservative].' She said that sometimes, at home, she was called Tor by her family. 'But that's very posh,' I say, thinking of all the Sloaney Tors I meet, and she asks excitedly, 'Is it? My boyfriend calls me Tor as well, Is that posh?'

The two stories that all the tabloids would kill for are 'Spice Girls Break Up' and 'Posh Spice Marries ManU Star', so I did my best, but she spent the entire interview fending off, with practised ease, the slightest hint of either one. The Spice Girl gang is notoriously outrageous and naughtily behaved when their Girl Power is five against one and they can smear princes with lipstick and pinch their bottoms and ('It's easy when there's five of you'). So do Spice Girls row, and bitch at each other? Do they fight? Oh but of course they do. 'Everybody wants to write, everybody wants to have a go at singing, everybody wants to have an opinion. We're all different and we've got different tastes musically. We have flaming rows about tiny things, bits of words that we want to put in lyrically.' But Spice Girls know how to kiss and make up. 'Right from day one we've had an American attitude. If there's something wrong, we're just open about it. It sounds disgustingly sick,' she says composedly, 'but we're more like sisters than anything. We've traveled all over the world together, we've lived together, we've written songs together: you become so close with one another.'

She's on a sugar-and-spice roll here: 'At the end of the day, it's all about respect. Five heads are better than one,' she begins. 'Five heads are better than two...' but I nip in with a Beckham question before we have to plod through the rest of the maths. Is she looking forward to being a football wife? She gives me a scornful look and says: 'Well I don't intend to dye my hair blonde.' She says: 'Some reporter came round to our house and asked me about being a football wife - he was comparing me to Sheryl Gascoigne. I couldn't believe it.'

But what was all that wedding-dress business in the newspapers? 'Oh!' she said. 'I'd bought a dress for a show I was doing, and I needed it altered. So I took it to my mum's friend's shop, which is a bridal shop.' So, Victoria exits a bridal shop, a quick paprazzo takes a picture, and lo - 'Posh Spice Marries David Beckham' exclusives roll through the presses. She was somewhat miffed. 'What made me most upset is I thought, "My goodness - if I was going to get married, if I was buying a wedding dress...' She's too polite to finish the sentence, so I will: 'I wouldn't buy one from the local high street.' Instead she says: 'I mean, no disrespect - but... you know!' Yes, we know, Victoria. Miuccia Prada and Tom Ford would be on the line in seconds, not to mention your new best friends Christian and Karl and John.

A football wife maybe - but she'll never become a football fan. The Theatre of Dreams passes Victoria completely by, and she'd have a hard time comparing notes with United diehards on, say, Beckham's 60-yard Goal of season Kick from his own half at Selhurst Park. 'I call what he does football competitions. I can never remember what they're supposed to be. Football games? Football matches. Oh well, it's all a performance, innit?' She laughs and puts a luvvie voice on: 'You got a show tonight? Performing tonight?'

She says: 'I like him for him and I don't care what he does as long as it makes him happy.' So she isn't thinking of moving to Manchester? She pulls a face. 'Not many nice shops in Manchester. No Prada and Gucci in Manchester.' Maybe Becks should move to Celtic, then, and she could shop in Glasgow? She pulls another face (and who would blame her?) and says silkily, 'Or Italy.' Oh, now you're talking. Ecco! - Prada and Gucci. Posh's dark eyes go dreamy for a second, the way they do when the words 'Prada' and 'Gucci' come to mind, which they clearly do a hundred times a day, and they suddenly focus into shock and she leaps to her feet yelling 'Oww! Naoww!' like Eliza Doolittle. 'What? What?' I ask, startled, and she howls aloud: 'Don't put that. Leave it out. Promise me you'll leave that out. Hate-mail. I'll get such hate-mail from all those Manchester United fans. Oww!' She really, really means it. 'I get enough as it is! If they think I'm persuading him to move to Italy. 'I'll get sacks of hate-mail.'

By this time, I am laughing fit to bust at her consternation, but then she gives out another anguished yell as an even more horrible thought strikes. 'Even Alex Ferguson'll start sending me hate-mail,' she says, and we both go quiet.

Poor little Posh. She shouldn't have a care in the world. She's young, rich, successful, famous and gorgeous. She's beloved by Becks, adored by fans, cover-starred by Tatler and clothed from head to toe by Prada and Gucci - and what's her problem? She's haunted, like every football manager in Britain, by the terrifying spectre of Manchester United's Alex Ferguson.

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