A sound not heard since the early Eighties floated over the Thames one recent morning - that of posh young Tories braying with delight.

"It was like a donkey sanctuary," said the Telegraph nark infiltrated into Boris Johnson's victory party in the Millbank Tower. "Lots of very drunk public schoolboys alternately booing and cheering at BBC News 24 as first Boris then Ken came on. You know, like very, very drunk."

There was caviar, too, and the odd oyster, as the Conservative Party celebrated its May 1 capture of City Hall and the end, or at least the beginning of the end, of its wilderness years. It was as if the half-forgotten era of the Sloane Ranger and soft-top Golf GTi had briefly returned.

Like the man himself, the friends of Boris were posh and proud. London's new mayor went to Eton and Oxford, flicks through Herodotus on the Tube and cannot finish a sentence.

That makes him posh by most people's reckoning.

His boss, David Cameron, went to Eton and Oxford, is a member of White's (like his dad) and is married to the daughter of a baronet. That's dead posh to most of us. And both he and Boris were members of the Bullingdon, a posh, if daft, Oxford drinking club.

Labour tried to pin this on both Boris and Dave (as the leader of the Tory Party likes to be known). Out came a now-notorious picture of them posing with the rest of the Bullingdonians, looking like a gathering of the Oxford branch of the Spandau Ballet Appreciation Society. It reeked of arrogance and entitlement, but no one cared. Labour played the class card and lost.

Something seems to have happened. Poshness is no longer the political millstone it was - and that's because poshness isn't what it was. Boris may be a Balliol man, but he lives in Islington in north London and calls people "mate." Dave could buy his kids their own public school but sends them to a state instead. As for his wife Samantha, she has a dolphin tattoo and grew up near Scunthorpe in the north of England - although in a bit of "near Scunthorpe" that has been in the family since 1590.

Poshness is now a more fluid concept, and not nearly so offensive to the working class - partly because (and Margaret Thatcher should take a bow here) there isn't a working class.

During his mayoral offensive, Johnson was denounced as a buffoon, a Blimpish self-caricature. But the voters liked him; and so did young people who found his sense of fun appealing.

Cameron - sorry Dave - dealt with the posh issue head-on, arguing that it was where you were going that mattered, not where you came from.

Neither has fallen into the trap Douglas Hurd created for himself in 1990 when running for the Tory leadership. Faced with the democratically raised John Major, Hurd (Eton, Cambridge and Foreign Office) tried to play down his toffness.

"To hear him, you would have thought his father scratched a living as a tenant farmer on some desolate hillside," says political observer Anthony Howard. "His father and grandfather were both MPs and one was a baron or something."

Cameron and Johnson may be the beneficiaries of a subtle shift in opinion, which discriminates between stuffy Old Posh and more relaxed New Posh. Princes William and Harry are exponents of New Poshness.

In terms of DNA you don't really get posher than the second and third in line to the throne and the private reality of their lives must be a world away from that of the general populace, but they nevertheless convey an air of modern informality.

They go to football matches, drink too much in nightclubs and go out with middle-class girls called Kate and Chelsy. They don't look like they inhabit another planet socially - which in fact they do.

Toby Young might be described as New Posh, being the son of an eminent sociologist (later given a life peerage) but educated at a state school in north London.

He believes that the Reign of Terror - under which the really posh were forced to speak in mock cockney accents - is over.

"Cameron has neutralized the toff factor by being the Normal Decent Guy and emotionally available," says Young. "Boris is a pantomime toff. If he took himself more seriously his poshness would intimidate people, but his humor allows people to be impressed by his poshness - as they say, everyone loves a lord.

"There is the yearning deep in the British psyche to be entertained by these Wodehousian characters. The decline of deference is overstated."

The truth is, though, that Boris is not really posh at all. His dad was a Member of the European Parliament, after all.

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