Right on! So, is it finally cool to be a Conservative?

Joan Collins's face may be falling, but for once it's not at the state of the Conservative Party. Boris Johnson's victory over Ken Livingstone last week was the first shake of the champagne bottle that uncorked a week-long Bacchanalian fiesta of fine plonk, posh grub and celebratory glad-handing for supporters of Britain's newly-successful Opposition.

The jollities began in the 29th-floor bar of Millbank Tower shortly before midnight on Friday 2 May. Arriving by limousine, the triumphant Bozza strode in to the strains of "Jerusalem", played by an all-blonde girl band in black dresses. Guests, among them David Cameron, Sir Tim Rice and Boris's family, wolfed down fizz, caviar, sashimi and Harrods oysters. The centrepiece was a soaring ice sculpture. Festivities continued until dawn.

With the exception of Mr Johnson, who had to go to City Hall to be sworn in as the capital's Mayor the following morning , and a handful of hardy souls despatched to Crewe to prepare for the crunch by-election, the partying has continued pretty much non-stop, ever since. For Conservatives, for too long used to the bitter taste of defeat, the good times have been an awful long time coming.

The celebrity bash of the week, eclipsing Hello! magazine's 20th anniversary, which Ms Collins also attended, was The Spectator's 180th birthday on Wednesday night. Some 450 guests – among them the Shadow Cabinet, Mr Johnson, Mr Cameron, Nick Clegg, an array of power brokers, B-listers and very many beautiful women in tight silk – crammed into a ballroom at the West End's Churchill Hyatt Regency to raise their flutes of vintage Pol Roger to the rude health of the Tories. Samantha Cameron worked the room. Andrew Neil held court with donors such as Sir Stuart Wheeler (sadly flying without his daughters Jacquetta or Charlotte) and Howard and Aidan Barclay. Those running laps of the two champagne bars, the cheese table, the sushi station and four buffets included Ms Collins, Anne Robinson, Duncan Bannatyne, Michael Winner, Emily Maitlis, Alain de Botton, Barry Humphries and his son Oscar, Nicky Haslam, Kirstie Allsopp, Kathy Lette, Stelios Haji-Ioannou the Tatler editor Geordie Greig, Elton John's agent Gary Farrow (a devoted Tory) and even Gordon Brown's supposed close mucker Mariella Frostrup.

The actor Steven Berkoff posed with Mr Cameron, having recently renounced his lifelong support for Labour: "I'm just fed up with all the lies. I think Brown is a fraud. I like the cut of David Cameron's jib."

Across town in Notting Hill, Frances Osborne, wife of the shadow Chancellor George, launched her new novel with the help of Boris Johnson's sister, Rachel. The latter described her sibling's victory thus: "He has brought Tories in the capital to a collective orgasm." Going by some of the facial expressions, she may be correct.

Today, as the hangovers set in, a pertinent question remains: was there, in the perfume-drenched, champagne-soaked air of this week's post-election celebrations, a political and social revolution taking place. Could it suddenly, after all these years, have finally become cool to be a Tory?

Let us consider the evidence. Mr Cameron's celebrity-studded revelry evokes those halcyon mid-Nineties days of Cool Britannia; of Britpop, the Spice Girls and that electrifying image of Noel Gallagher and Meg Matthews in Downing Street. When – in the shape of Tony Blair, who some consider to be Mr Cameron's natural soul-mate – a political leader was last well-and-truly "trendy". There are, of course, still vast swathes of Britain where admitting to support the Tory cause will see you set on fire. But the new generations have short memories; for them the Tories are not abidingly associated with the miners' strike, 14 per cent interest rates, negative equity, Black Wednesday, sleaze, and a tired and weak leadership.

Across the country, there are signs that the formerly flabby Tory movement has at least become socially acceptable, and is acquiring a cultural and political cachet among the under-40s – a group far removed from the "blue rinse" pensioners who make up the party's core support.

Legions of young candidates, many of whom brush up rather well, as they say in clubland, have been crowbarred in to contest the next general election, such as Zac Goldsmith, Shaun Bailey, Annunziata Rees-Mogg, Jeremy Brier and Priti Patel. The "public face" of Mr Cameron's office is that of his 30-year-old press aide Gabby Bertin – glamorous, formidable and occasionally haughty. Very new Tory.

"This year we have seen massive growth in universities," claims Michael Rock, chairman of Conservative Future, "particularly in Newcastle, Lancaster, Leeds and Manchester. We have always been strong in York and the University of East Anglia. And last year we set up a City Future branch which has signed up 1,000 young professionals."

How did this happen? In 1997, the widespread loathing for successive Conservative governments pushed many Tories in to denying reality. "I remember going to the Central Office on 1 May 1997," recalls the current editor of The Spectator, Matthew D'Ancona. "There was a great big crowd outside, cheering and booing as the results came through. I heard one of them shout, 'How do you feel now you bastards?' That was a moment of revelation." Mr D'Ancona recalls that large parts of the party had lost touch with Britain's altering social fabric: its multi-ethnicity, the fight against under-representation of women, the sexual freedom of consenting adults.

Part of the problem in the Nineties was that the rich and the glitzy – precisely those who can offer political parties the money and column inches needed for victory – wouldn't touch the Conservatives with the proverbial filthy stick. A decade ago, unless you were invited to Lord Archer's flat for shepherd's pie and Krug, the fare offered at Tory fundraising shindigs involved warm white wine, bowls of peanuts and perhaps prawn cocktails.

Grand occasions might be graced by the presence of a dance band, to project Sinatra numbers. Then, in 2004, a quiet revolution began: Michael Howard's party treasurer, Lord Marland, hired Jack Soames, a smart public relations executive, to drag Tory fundraising events kicking, and hopefully screaming, into the 21st century, by making the events fun and – crucially – getting attractive, genuinely popular celebrities to turn up.

"The small fundraisers in towns back then were known as the 'cardboard chicken circuit', on account of the food served, which was an abomination," explains Mr Soames. "You had to do it with an extreme and rare goodwill. The tickets were cheap and not many people wanted to go. The party was very short of money. "Lord Marland recognised that to raise funds you've got to make sure people have fun. To raise ticket prices there must be better food and drink, better music, better people there, the chance to meet Bryan Ferry, Tamara Mellon, Eddie Jordan, Marco Pierre White, and get in the pages of Hello!. There was a need to woo younger, cooler people, luxury brands, and the new leaders of business such as David Ross of Carphone Warehouse. If you serve mojitos before dinner rather than buck's fizz, you're sending out a message."

The organising committees of "senior women" were sidelined. The venues became edgier – Old Billingsgate Market instead of Park Lane. Ties were banned. Drinks were organised by the former MP Phillip Oppenheim, now owner of a Cuban bar. It was "an uphill battle", but the transformation gained momentum and Mr Cameron's younger team is attuned to the so-called "Killers generation" (named after the US rock band). It has built on Lord Marland's progress through the efforts of Sally Hendry, who organises the revamped Black and White Ball and is the wife of the shadow Energy Secretary Charles, and the political hostess Anne Jenkins, of Women2 Win, and married to the MP Bernard.

The Cameroon movement's cultural currency is enhanced by the likes of Nicholas Coleridge, the managing director of the magazine publisher Condé Nast, and Dylan Jones, editor of GQ. Business is climbing aboard: Barclays Wealth and Pol Roger sponsored the lavish Spectator party, while Mr Cameron has a raft of rich businessmen funding the offices of his frontbench team.

This week he announced that to better understand manufacturing, Conservative policy teams will be embedded in Rolls-Royce – whose non-executive chairman Simon Robertson funds George Osborne's office to the tune of £75,000, and has donated £200,000 to party coffers.

"All the arse-lickers who want to be near the centre of power are starting to come over," says the former Conservative MP Michael Brown. "All we need now is Richard Branson. And Rupert Murdoch, who will back the probable winner."

Mr D'Ancona believes that, "with Boris's triumph, the decontamination of the brand is complete". Boris "captured the English optimism and confidence that people find so appealing. Labour miscalculated with the 'toff' attack: people didn't see an Etonian member of the Bullingdon Club but someone who speaks like a human being and not a speak-your-weight machine. But there has been an exaggerated sense that Brown is finished. Governments do not fall that easily."

For the Tories, however, there is a downside to flirting with celebrity. By definition, all fashions are transient. Support can be fickle or ill-fated; Noel Gallagher, the symbol of "Cool Brittania" in 1997, has since denounced Tony Blair as a "cretin".

Yet in the short term at least, the endorsements of David Cameron by businessmen and celebrities contribute to a wider atmosphere of cultural acceptability. "These [drinks] parties you're talking about – that's beltway stuff," says the leathered pollster Sir Robert Worcester, founder of MORI. "Like what happens at the despatch box, it makes little difference to the public. But it matters to the coterie and the donors. What is of greatest impact on the next general election is that the Tories have more than 10,000 councillors, more than double the Labour foot-soldiers on the doorstep. The thing to remember is that oppositions don't win elections; governments lose them."