Amid the rococo interiors of London's finest Georgian mansion, a privileged few will gather next week to celebrate the 300th birthday of the magazine that believes itself to be the oldest in the world.
As guests from the worlds of politics, business and the arts mingle beneath its sweeping staircase, Lancaster House in St James's will have seen nothing like it since George Bush senior, John Major and Mikhail Gorbachev met there with other global leaders 18 years ago, to discuss the future of the world.
For Catherine Ostler, the new editor of Tatler, it will be a big night. After all, this is the title that prides itself on its unrivalled insight into the party habits of the rich and powerful.
And yet she views the idea of hosting the party to end all parties with some trepidation.
"You keep talking like that and I'm not going to go," she says. "Oh God!"
Exactly three centuries have passed since Joseph Addison and Richard Steele, two great pioneers of British journalism, founded a publication to carry the gossip from the coffee houses of St James's in the turbulent reign of Queen Anne.
At the Vogue House headquarters of publishers Conde Nast, they have been planning this landmark occasion for years, the date circled in diaries long before Ostler was appointed editor in February.
During her first weeks in post, the prospect of the 300th anniversary issue of the magazine sat "on the top of the hill like a big elephant", she says.
But now, on the desk before her, she has the remarkable triple gatefold cover that arrives on news-stands today.
The cover girl is Her Majesty herself, in postage stamp profile and given three creative treatments that reflect Tatler's aristocratic connections alongside its love of luxury and impish behaviour.
"300 years of Mischief" runs a cover line and the second of the three regal images owes much to Jamie Reid, the designer of the Sex Pistols artwork.
This naughtiness is not contrived: Tatler's history is a chequered one and during the Sixties it was run by a moustachioed playboy of a conman called Guy Wayte who was collared by the police and appeared in the press beneath the headline "He duped Mayfair".
The 300 years claim is a bit of a stretch though, given that Addison and Steele's incarnation of Tatler lasted barely two years and the title did not re-appear until 1901.
According to Ostler, who has immersed herself in the history of her magazine, Tatler has always had a cover star of the moment, from Tallulah Bankhead in the Thirties and Vivien Leigh in the Forties through to Elizabeth Hurley and then Keira Knightley.
"But the one who was consistent was the Queen," says the editor.
"Right back to when she was a little girl clutching a dog."
The references to mischief and punk, she says, are "because - given that we had put the Queen on the cover - I didn't want it to be too reverential and look like Majesty magazine".
Nonetheless, readers of this "special anniversary collector's edition" are offered features on the "three first families" of Tatler; namely the Goldsmiths, the Guinnesses and the Spencers.
There is an interview with Lady Annabel Goldsmith, Mary Killen has revisited her memorable 1985 feature "Guinnessty", and former Tatler editor Tina Brown has described how Lady Diana Spencer embodied the magazine in the early Eighties.
"They were moving away from old England but then suddenly there arrived this creamy-skinned, quiet country mouse, daughter of an earl," says Ostler.
"It was the last person they would have imagined would make a decade take off in magazine terms and it was Diana."
There's another well-heeled interviewee in the issue, namely the Mayor of London Boris Johnson, who was asked not about "bike lanes and bendy buses" but "Do you actually like what you are doing?"
It's the type of piece which other editors might have held back as prime property for the next issue but Ostler, with her Fleet Street background, likes to crack on.
"Having not been very long out of newspapers I still have the temptation to squash everything in as quickly as possible," she says.
Her previous role was as editor of the London Evening Standard's well-regarded ES magazine, meaning she swapped offices with the new Evening Standard editor Geordie Greig, who had been at the helm of Tatler for a decade.
When Greig announced his intention to leave, Nicholas Coleridge, the managing director of Conde Nast in Britain, identified Ostler as the condition of his departure.
Having begun her career at Tatler, only two weeks after graduating from Oxford University, Ostler was well-known at Conde Nast - indeed the company's general manager is her husband Albert Reid.
She was the magazine's features editor before joining the newspaper industry where she worked for The Mail on Sunday, the Daily Express, The Times and the Daily Mail, then edited ES for more than six years.
In her brief time in charge of Tatler she has produced several scoops, such as a recent interview with royal bride Sophie Winkleman.
"She turned down £600,000 from Hello! and did us instead," says Ostler.
"She trusted us that we would make her look good and give her a fair run which I think we did. No one is going to do Tatler for the money."
At Ostler's request, the actress Emily Mortimer wrote a tribute to her late father John. Asked how she pulled off that coup, the editor is coy, whispering "She's a friend. Oxford".
In Ostler's first issue in charge she broke with recent tradition by having Liz Hurley photographed full-length and outdoors. She even attended the shoot herself.
Liz, in turn, delivered up headlines by talking about the opportunities provided by a soft rug in front of an open fire in a country house.
The media was also agog after Tatler interviewed Charlie Brooks about the extraordinary social whirl that he enjoys with his wife Rebekah (nee Wade), now the chief executive of News International.
The couple, it was revealed, fly to Venice by private jet for lunch at Harry's Bar.
"She hadn't co-operated, wouldn't give quotes or be photographed or anything," concedes Ostler, when asked for Rebekah's view of the article.
"I heard on the grapevine that she was slightly annoyed with it, but we thought he was great. The piece was very enthusiastic about him."
Where will Ostler fit into Tatler's long story?
She praises Tina Brown for being the editor who "set the pace for the modern Tatler", putting Miss Piggy on the cover and creating a magazine that Conde Nast decided to buy.
Mark Boxer was the former Sunday Times cartoonist who drove up circulation in the mid-Eighties and "everyone loved him".
Jane Proctor, who gave the young Ostler her first break and including pictures of a naked Anthea Turner, "made it very glamorous and talked about".
Ostler wants to bring in more politics and has hired the Tory culture spokesman Ed Vaizey as a columnist.
Most of all she wants her Tatler to reflect the journalistic traditions of its founders, who in 1711 went on to set up The Spectator as well.
"I think Tatler has been and should be the journalist's magazine. It was sort of invented here, Addison and Steele were the first celebrated journalists and I love that."