WHAT is it about Posh Spice that had 8.3 million of us glued to our TV screens to watch the fly-on-the-wall documentary about her, Being Victoria Beckham, this week?

She has about as much talent as your average local pub karaoke entrant. Anyone who watched her miming, very badly, on stage will know she couldn't hold a candle to any of the last 25 plucky finalists on Pop Idol - in fact, she would have found it difficult to get past the early auditions.

Even her old performing arts teacher admitted there were much more talented girls in her class who ended up singing on cruise liners for a living. Yet Posh is the one with the record contract, multi-million pound bank balance and her face all over the magazine covers.

Not everyone even finds her attractive. "She has horrible, huge flared nostrils and bad skin," said one friend, the next morning. "And she's positively skeletal," said another. But we all watched the programme, and we were all talking - or rather bitching - about it next day.

We grimaced at her gushing portrayal of herself as a wonderful, doting hands-on mother and superstar housewife who refuses to employ a nanny or cleaner. For most of the programme, she travelled the world, making and promoting her new album, while her mother and mother-in-law were left at home holding the baby - and the mop and bucket.

Those of us who have screamed and screeched through labour were aghast when she announced smugly: "I loved giving birth, I really enjoyed the whole experience." It was her husband David Beckham who reminded her that she didn't actually give birth, as she had booked in for a Caesarian: "You didn't feel a thing," he said.

At times, the conversation was so banal that, as one TV critic put it, we felt our brain cells expiring while watching. But what people are really fascinated by is Victoria and David together.

Apart, this former Spice Girl and Manchester United footballer would attract the attention of a few teeny-boppers and football fans. But together, their fame is magnified a million, trillion, zillion-fold.

The secret of their success is that, beneath all the glamour and the artifice, this is a couple obviously in love and devoted to one another. That makes them a rare role model for the younger generation. And it fascinates the rest of us.

For that alone, in an age of rocketing divorce rates, we can forgive the tacky, flash lifestyle, vulgar taste, irritatingly banal ramblings and contrived glossy image.

The best bits of the documentary were when they talked about each other. He touchingly described her as his rock: "She makes me so happy," he said simply. "That is why I'm playing well and doing all the things I'm doing."

And I actually believed her when she said: "If he ever left me, I think I would die of a broken heart."

What the Beckhams genuinely value above all their riches is their relationship and their family. Which makes me think that, contrary to public opinion, they're not so stupid after all.