Posh or common? These days, profession and breeding don't come into it. We instinctively know where we fit, says Cayte Williams
The unthinkable happened this week and it struck at the very core of our Britishness. It had nothing to do with Euros or Emus or Belgian taxes on babies. It was far worse than that. Someone in Whitehall decided to change our class structure and it has started a rash of national navel- gazing. What exactly do our Scary Spice pierced bellies or Hermes belts say about us now?

The Office of National Statistics has presented us with a new system of defining social ranking based on jobs, earning potential and prospects. For example, estate agents are now in Class 2 where previously they were off the social scale altogether. Pop stars and entrepreneurs are now Class 1 whereas Princess Margaret - classed as the long-term unemployed - is Class 8. Now, we're told, pop stars, actors and models are the new aristocracy while the Blandfords and Bristols belong on the B-list.

Of course the old class system was past its sell-by date (in fact social strata maps were last drawn up before the First World War), but at least we used to know what was common or classy. Princess Diana was classy because she wore her collars turned up and talked posh; Hilda Ogden was common because she spoke with a fag in her mouth and never did her hair; Hyacinth Bucket thought she was classy although she was common and Bet Lynch thought she was common although she was classy.

Even in the Sixties, when toffs and tykes really started mixing, you knew who was who by their accents. David Bailey and Terry O'Neill were your "blimey" boys: working-class heroes on the gravy train and they loved it. Their otherness made them special.

Now it's not so easy. Posh behaves like common and common behaves like posh. Mick Jagger is the new breed of Lord, chasing skirt around the world the way the old Laird once chased a scullery maid. Posh Spice has more money than the Prime Minister, Meg Mathews (common as muck) shares a gossip column in a national newspaper with Tara Palmer-Tomkinson (classy as Chuck) and Ginger Spice has turned into pop's answer to Fergie.

Classy and Common are mixing, and it's not like oil and water - it's more like Tesco's marble slab cake. In Blair's Britain we all think of ourselves as middle-class. Window-cleaners eat sun-dried tomatoes with pesto sauce; lorry drivers splash out on Calvin Klein undies and everyone knows about Chardonnay. Unfortunately it's fast becoming the Leibfraumilch of the Nineties, while German wines like Riesling are making a comeback.

We all think we know what classy is - we get it off the telly. Don't know what to cook? Ask Delia. Don't know how to decorate? Ask Changing Rooms. Don't know what to wear? Ask Style Challenge. Good Taste comes at us from all four channels (tacky could be Channel 5's only hope), except that it's all become so desperately, well, common. "I went to three dinner parties last week," one friend lamented, "and every one served Delia's recipe of root vegetables with rosemary, every hostess was wearing a devore velvet scarf, and everyone's walls were painted in Helium."

In fact, we've all become so dreadfully middle class that the only way is down. Say hello to Ironic Common - no-taste as good-taste. Kate Winslet serves bangers and mash at her wedding; the premiere of the film The Acid House was awash with beer and curry, and the coolest nights are spent at home scoffing Angel Delight and playing Ker-Plunk. Ironic Common means you'd rather spread brown sauce on your bangers in your local caff than sit in a posh restaurant eating something called "jus".

Flash is just not fash. Marco Pierre White might just hit on this with his latest eaterie, The Titanic. Contrary to popular opinion, the uberchef is not classy (he's sort of a gastronomic Peter Stringfellow - daft hair, daft pout, daft tantrums), and this latest venture advertised it from the billboards. The theme for the opening night party - "overdressed and overboard" - was very common. Why? Because it represented debauchery (finding a tragedy that amusing) and excess (inviting Trudie Styler), two things that right now are desperately common.

Even Harvey Nichols, once the Mecca of class, is now five floors of dodgy taste. There was a time when department stores were as idiosyncratic as their buyers, but now they're basically mini-malls for the Kleins, Laurens and Hilfigers of this world, the same tired old names that are a million miles from exclusive. Now all department stores are common, from Harrods (number one common) down to Liberty (borderline common). The only place classy people shop is in "boutiques", places with names like The Pineal Eye (for clothes) or Villandry (for food).They know that no Klein-lover or Delia-chef has ever heard of what they've got in their carrier bags.

But never fear. Although what's classy comes and goes, there are still those common perennials we can cling on to for comfort. We know that Posh 'n' Beckham's wedding will be a style disaster, that Tamara Beckwith is living proof that money does not buy taste and that GMTV, Acrylic and puffed sleeves are a total no-no.

We take solace in the ubiquitous common-ness of net curtains, pebble dash and stone cladding; tandoori tans, mullets and stone-wash denim; Aberdeen Steak House, Harvester and Beefeater; the Daily Mail and the Millennium Dome. The latter, in fact, has become a mascot of Common. Is anyone surprised that McDonald's has become a major sponsor? No. Is anyone astounded that Britain's talented designers wouldn't touch it with a barge- pole? No. The vulgarity of the Millennium Dome is that only those not rich, clever or imaginative enough to spend their New Year in Sydney, Sao Paulo or at home will go.

Our class and standing in society might be shuffled around like a pack of cards by civil servants, but we still know where the aces are and can spot a joker a mile off. The day pop socks, Christopher Biggins and Middle England become classy will truly be the time to cash in the chips.