There are few people more likely to stage a riotous 30th birthday bash than Prince Harry and Pippa Middleton, as the Duchess of Cambridge will doubtless discover at her landmark celebration this weekend.

Dinner followed by an ’80s-themed cocktails-and-karaoke disco to be held at a secret venue in London is, according to Grazia magazine, the run of events. It is unlikely, given the extensive coverage, that any of this really remains “a surprise” for Kate (whose birthday is on Jan. 9), but with Prince Harry in charge of entertainment, it is nonetheless set to be a raucous night.

What Prince Harry, dubbed the Playboy Prince, doesn’t know about enjoying himself probably isn’t worth knowing. Pippa, on the other hand, brings professional expertise as a party organizer with Party Pieces, her parents’ company, and as editor of the Party Times website.

On the eve of her birthday, Prince William and Kate will make an official public appearance at the movie premiere of War Horse, directed by Stephen Spielberg, at Odeon Leicester Square. Afterwards according to Now magazine, she will be whisked away “to party.”

“In many ways, this is going to be Kate’s last chance to let go like she did back in the old days when she and William first met,” a royal mole told Grazia magazine. “The party has been months in the planning. Pippa and Harry have been in the thick of it, and have recruited a bunch of friends to help. The guests have been sent ‘save the date’ cards, and told that it will probably be in London. Given the people organizing it, you can be sure it will be brilliant.”

Pippa certainly has a flair for originality: for her New Year’s Eve party last week, attended by William and Kate, Pippa hired a Laplander kata—a tepee-style shelter made of animal hides—for ₤3,000, and pitched it in her parents' back garden in Berkshire. Around 100 guests ushered in 2012 in what was described as a “canvas palace,” making full use of the dance floor.

Her plan for Kate’s 30th is said to be a “pop-up” venue, as opposed to an established setting. The bar is to be organized by friends Charlie Wilkes and Duncan Sterling, who own the zany Bunga Bunga Pizzeria in Chelsea, and Maggie’s Club (named after Margaret Thatcher), which specializes in ’80s-themed cocktails like the Ferris Bueller Fizz, the Pacman Martini, the Back to the Future, and the Walkman.

The ’80s theme pays tribute, of course, to the decade that Kate was born—a decade that is all the rage right now in Britain and the U.S. But in truth, the royal family has always loved costume parties.

Prince William’s 21st had an Out of Africa theme (his father dressed as an African tribal king and the queen in a Swazi costume). The Duke of Duchess of Kent’s children, Frederick and Gabriella Windsor, primped for a pre-revolution, pre-guillotine French court, with guests arriving in stacked-up wigs and dresses with hoops of silk, served by footman and observed by human statues. Princess Beatrice chose an 1888-themed masked ball for her 18th and dressed in a blue taffeta bustle, while Prince Harry wore a fedora and Al Capone zoot suit for his then-girlfriend Chelsy Davy’s 21st in Cape Town.

The queen is said to have advised Prince Harry against having a theme for his 21st (after he wore an Afrika Corps uniform with a swastika armband to a colonials and natives–themed party in 2005).

Prince Harry’s reputation for high jinx and close-to-the-knuckle humor plays well with the crowd of trusted friends and family with whom Kate and William can relax. The couple tend to avoid the glitz of show business in their inner circle—with the exception of David and Victoria Beckham, who have been invited. Other expected guests are Thomas van Staubenzee (“Van”); Guy Pelly, the mischief-loving owner of Mahiki and Whisky Mist; the van Cutsems; Lord Percy and his sisters, the children of the Duke of Northumberland; and family members such as Zara Philips and Mike Tindall, and Kate’s brother James, all dressed for the occasion.

While Kate will also get into the spirit, it is unlikely she will be embracing the yellow hotpants, sequinned turquoise halter, and florescent-pink legwarmers that she wore to a charity Day-Glo midnight roller disco she co-organized in 2008. Kate’s style has conspicuously moved up a notch in recent months, as she takes on the increasing seriousness of her role as a senior royal.

In that vein, Kate has asked friends not to lavish her with gifts but to make donations to charity instead. Despite this, Prince William has reportedly been looking at both watches and jewelry, in addition to commissioning a portrait in oils by an as-yet-undisclosed artist. The queen is expected to give her a tiara from the royal collection, but private gifts from the queen are not made public, according to Buckingham Palace.

The Palace also declined to comment on whether any of the older royals would attend the Duchess of Cambridge’s 30th birthday celebrations, saying: “There is no official party, and anything that goes on will be in private. I’m sure she will be celebrating, we just can’t confirm anything.”

However, a royal source has told Grazia: “It’s going to be a party of clashes in every way. On one hand, there are all these exquisite royal trappings, and on the other, Pippa is planning to top off the party with a karaoke session. Kate needs to enjoy herself while she can, though, so she can be forgiven for belting out a few Duran Duran and Madonna numbers on her birthday. It’s all going to get pretty serious afterwards.”

Kate is used to the heat of the spotlight, but the attention on her 30th birthday will mark the beginning of an extended period of time alone performing official duties: in February, Prince William heads to the Falkland Islands for a six-week Royal Air Force tour, piloting search-and-rescue helicopters.

Soon after that, the duke and duchess will embark on a Diamond Jubilee tour of the South Pacific. As she steps into her fourth decade, the more conservative-minded in Britain will no doubt be tapping their watches and asking if 2012 is the year that the Duchess of Cambridge will be leaving the partying behind her and settling down to concentrate on a family.