‘Do you mind!” thunders a middle-aged woman in a substantial fascinator. It is teatime, just after the Gold Cup, and she has emerged daintily from the royal enclosure only to have lager sloshed across her kitten heels. The slosher - whose own fascinator, like her, is somewhat the worse for wear - laughs in her face.

“Do you maind!” she imitates. Her boyfriend and hangers-on all cackle. “What’s got into you, love?”

“Well really . . .” posho scowls, hurrying off to the ladies to sponge off her shoes.

If you are in any doubt as to why the class divide still haunts Britain, I suggest you pop down to Royal Ascot, as I did last week.

Forget your dreams of Britain as a classless meritocracy. These days Ascot is where the haves meet the chavs head-on. In fact, it’s a turf war. In the royal enclosure the cream of Britain - ie, rich and very thick - wear top hats and tails, talk form and sip their champagne. Outside - in the numerous Pimm’s bars and beer gardens - first-generation lower-middle-class types get wrecked in the sunshine. Boobs out, legs akimbo - Eliza Doolittle needn’t have bothered with the elocution lessons to fit in here.

As you might imagine, tensions are rife - not least among the organisers. Worried that standards were tumbling downmarket, last week they issued stricter diktats on the dress code. Knickers must be worn (but not seen) by all women; and for the royal enclosure it’s formal morning suits for the men, while ladies require skirts or dresses but no bare legs, no exposed backs, and dress straps at least an inch in width.

It hasn’t put them off. While the credit crunch is cramping the style of the banking elite, the nonUs are still enjoying all the benefits of a recently booming economy. Rising fuel bills won’t really kick in until the winter and in the meantime this lot want to dress up, show off and think nothing of paying £4.80 for a glass of Pimm’s. Receipts for the five-day event are approaching record highs.

It was obvious that trouble was brewing as soon as I got on the train at Waterloo. The floor was already puddled in champagne and the air was thick with booze and the reek of fake tan. The chattering girls were defiantly strapless, backless and, in some cases, thighless. “I’m buggered if I’m not going to get a tan,” said Claire, 32, a manager for Currys, up with friends from Hastings.

At the ground it is ladies’ day, although ladies are hard to find. Anatomically, they certainly fit the bill. With all those akimbo legs and - despite the new rules - a distinct lack of knickers, I get more than one Technicolor eyeful of proof. Frankly, it’s more like ladettes’ day, with women of all ages plonked on the grass, necking from champagne bottles, squired by men in nightclub bouncer suits and shades.

The only prop that unites the classes, or the women at least, is the fascinator. How best to describe a fascinator? Essentially, they are hairclips with attitude. Bit of feather, bit of netting, stick it on a clip, pop it on your head and - voilà! - you look like a chocolate box. It is the must-have look of the day.

Despite this nod to decorum, the vibe is decidedly Torremolinos. In the gents, much guffawing and sniffing is coming out of one of the stalls. Two fatties eventually bundle out rubbing their noses. “You want some cash for that?” says one.

“No worries, mate. I’m a plumber: £80 an hour plus Vat,” laughs the other, to scandalised looks from the top-hat brigade.

“You should be ashamed of yourselves,” one says. “Piss off,” they both shout after him.

I can’t help but wonder: why bother getting all dressed up like the posh people only to get insulted by them. Why are you here, I ask a tattooed woman outside. “The hats, mostly,” she giggles. “It’s a bit of fun.” And the smart set? “So rude,” she tuts, while her friend comes rushing over, shouting: “Shall I get me tits out for The Sunday Times?”

I decide to have a stab at getting into the royal enclosure. While some goon in rented Moss Bros shuffles on in, I’m stopped and told that I’m dressed inappropriately. Apparently a Ralph Lauren suit doesn’t cut it, I sniff inwardly. But soon I find another entrance and by emitting a posh and purposeful, “G’day to you”, stride past the ushers.

Inside, the volume is tuned to a polite hush. The men are quite drunk (in that stiff, “I had polio as a child” kind of way) but the women hardly drink at all. Everyone is immaculately dressed and delighted to be in the presence of two queens - Elizabeth II and Helen Mirren. In here they take the racing very seriously. Outside, I had heard a woman at a bar say: “Ooh look, a horsey.”

Will Ascot survive the plebs, I ask a behatted gentleman. “Of course it will. You have to remember there are two Royal Ascots. This one - the proper one - and the one . . . out there,” he says with a dismissive flick of his hand. “I think we’re winning,” says his wife.

I’m not so sure. Outside the racecourse, Tiffany, resplendent in a Lycra catsuit, is handing out free passes for Spearmint Rhino, the lap-dancing club. Then, on the walk to the station, It’s Raining Men is booming from a pub garden that’s filling up fast with dancing revellers: chavs 2, toffs 0.

There you have it. A microcosm of the class war that leaves meritocracy in tatters. Some of us may still - just about - be united in terms of disposable income, but no government initiative will ever unite our opinions of what constitutes a good day out.

By the hamburger van, packed with racegoers stuffing their faces, I spot a miniature tower built of spit, fag ends and fake nails. It looks rather like a fascinator. Just the thing for Royal Ascot 2009.

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