A couple of weeks ago Trinny and Susannah strode on to the stage at a Dublin fashion event and one of them (it doesn't matter which - they're the same hellish entity) announced: “I think Irish women are the best-dressed in the United Kingdom!”

Ho, ho. Did you spot the little mistake there? People in the audience did. One or two gamely shouted back: “We're not part of the United Kingdom”. Whereupon Trinny replied: “Oh, sorry. Our geography's not too good. We meant northern Europe or whatever.”

Now this incident, aside from a paragraph in the Daily Mirror and a gentle write-up in the Irish Independent, has resulted in no mocking of Trinny and Tranny whatsoever. Why? When Jade Goody revealed that she thought Cambridge was in London, it was front-page news as we all wet ourselves with mirth, chortling: “God, these chavs are so STUPID”. When Christina Aguilera famously asked: “So, where's the Cannes Film Festival being held this year?” and Charlotte Church, on stage in Toronto, declared: “I love being in America!”, their faux pas were instantly immortalised on Dumbest Celebrities websites.

So how come Trinny and Susannah get off scot-free for not realising that Ireland is a republic? I'll tell you: it's because they are posh totty. And it is the law that posh totty get away with anything. Slutty clothes, nude modelling, bad language - it's all fine so long as you do it with the right accent. This is why T and S get to whack their baps out to pensioners in the middle of shopping malls, tell housewives that they've got “sagging tits” and squeeze complete strangers' buttocks and people merely break into polite applause. If a 14-stone single mother from Sunderland with a scrunchie tried that, she'd find herself in the back of a police van.

I always ponder this theme after a week of watching the Conservative Party conference, when even devoutly left-wing male friends who have been there for work say things such as: “It was dull - but there was a Sloaney piece who I wouldn't have minded a roll in the hay with.” What? Why? Where are your principles? I've studied this long and hard, and often the females they point out are not even that attractive. But they do have a £4,000 frock and a triple-barrelled name and that, sadly, is The Thing.

There's no point denying it: men, whatever their background, can't resist posh women. It's very upsetting. If I ever put on a tarty pair of leopard-skin heels, I'd be told I look like a hooker, or worse, Bet Lynch. When Theresa May did it at party conference a few years ago, she was “a fox” and the nation's males began hyperventilating, stuttering things such as: “I wouldn't mind a whipping from her”.

I've been noticing this increasingly of late. Another male journalist friend, ringing me from Tory conference this week, explained: “I wouldn't want to talk to them or anything. It's just that they're so well-groomed and proper, you'd just like to - er - ruffle them up a bit.”

Oh, please. There's more to it than that. Because when top-drawer women do “improper” things, you love that too. Lindsay Lohan and Britney Spears wear no knickers and they are “celebrity trailer trash”. Fragrant Joanna Lumley admits to wearing no knickers and prompts headlines such as “No underwear - and absolutely fabulous!” When Nigella wore only tinfoil for a magazine shoot (imagine the brickbats if Fern Britton did likewise), half the men in the country morphed into randy Labradors.

I'm beginning to see Trinny and Susannah as symbols of this country's double standards. Recently they visited a hospice in Surrey as part of a “Look Good, Feel Great” makeover event where Susannah, advising a patient about bras, promptly exposed her tanned breasts. Now, I know that it often does terminally ill women a world of good to have makeover treatments, so I'll make no cheap jibes there. But it is debatable how beneficial copping an eyeful of Susannah's big, brown, lusty speckled eggs would be to a woman in the final stages of her life.

Some say a backlash has begun against T and S because they've taken their kit off once too often, with one paper urging: “Do put them away now, girls”. Call that a backlash? Had, say, the downmarket Kerry Katona done a tenth of what they've done she'd have been hung, drawn and quartered by the tabloids years ago. Some naked clackers are more equal than others.

This is one of our country's curious contradictions: the more privileged someone is, the more we forgive them for gauche behaviour (cf, the Prince of Wales). It's not OK for Jade Goody, dragged up in poverty with a non-existent education, to say something thick - but it's fine for two boarding school-educated fashionistas, one of whom used to date Viscount Linley.

I do believe that Boris Johnson could make the most politically incorrect statement ever heard by the human ear, but because of the way he speaks, we'd slap him on the back fondly and say, “That's just Boris!” Contrast this with John Prescott, who became a national laughing stock with each new, flat-vowelled malapropism.

David Cameron wants to downplay the toffness in his Shadow Cabinet and has ordered his party to act humbly, not appearing to take victory for granted. We hear he is peeved that several senior ministers recently agreed to pose in expensive suits and cocktail dresses for Tatler under headings such as “Future foreign secretary” because it seemed arrogant. It did.

But, do you know what, Dave? I'd ramp up the poshness a bit more. We're still a dysfunctional, class-ridden country, and though we like to rail against privilege, we're bizarrely in awe of it. Things go in cycles - the Nineties was about Denise van Outen and Ulrika ladettes - but now we're bored of that and liking poshness again. Hence the backfiring of the anti-toff campaign in Crewe and Nantwich, and the strange popularity of Kirstie Allsopp.

It pains me to say this, but posh totty: your time is now. And as with most things in life, you won't even have to try.

Times Recommends

• In the real world, the public sector must pay
• Playing politics in a land of double Dutch
• Be like the plinth people: not set in stone