P-Middy's booty went viral on Twitter and YouTube, while her apparent flirtation with Prince Harry - the best man in only one sense of the phrase - saved the royal wedding from wholesomeness overkill. A new star, the people's choice, was born.
The reasons are simple. After years of patient courtship and forensic media examination, Kate is a known quantity and can now safely be parked in "domesticity" as the Duchess of Cambridge. Pippa is an enticing mystery. And possibly, we all like to think, a bit of a fruity one.
Was she really wearing butt-sculpting Spanx pants at the wedding? Or did she go "commando" in the Abbey? Did she fancy Harry, even a bit? Is she planning to cash in on her new-found fame, either romantically, socially or financially? What is her favourite colour? And are there any more photos of her in a bikini or dancing around in a mauve bra?
Here, the Evening Standard's authoritative and royally appointed* Pippapedia sorts the fact from the fiction.*not really
Philippa Charlotte Middleton is the second child of party planners Michael and Carole Middleton, born on September 6, 1983, a year after her older sister and four years before her brother. James Middleton is the only one of the siblings not to have acquired a nickname that makes him sound like an Enid Blyton character.
"Pippa" - or "Panface", as she was known at school, because, despite being pretty, she had a flat-shaped face -spent the first 10 years of her life in a four-bedroom Victorian villa in Bradfield Southend, Berkshire, before the family moved in 1995 to a large house in the nearby village of Bucklebury. Pippa, like Kate, was christened at the local parish church of St Mary the Virgin, and undoubtedly visited the local supermarket, run by Hash and Chan Shingadia, and the village hostelry, The Old Boot Inn.She was educated, like her sister, at St Andrew's School in Pangbourne, at Downe House (unlike Kate, there are no reports that she was bullied) and at Marlborough College. Ferociously athletic, she attended the latter on a sports/all-rounder scholarship.
Whereas Kate was known to her student contemporaries as "Kate Middlebum" or "Princess in Waiting", her younger sister attracted the enviable soubriquet "Perfect Pippa". A hard worker, she was also a forceful presence on the university's upper-class social scene, especially at shooting parties.
After graduating, she was briefly employed at a PR firm promoting luxury goods, before her impeccable contacts secured her a job working three days a week for events planner Table Talk: she repaid the favour by enlisting the company's boss, Jojo Browner, to assist at her sister's reception. Two days a week, Pippa edits Party Times, the online spinoff magazine of her parents' company, Party Pieces.
She took an active part in the post-wedding party - it was her idea to have vans serving bacon butties and ice cream in the palace quadrangle - as well as an eye-grabbing, train-wielding, bridesmaid-coddling role in the ceremony.
At Edinburgh the younger Ms Middleton hung out with the "castle crew" of heirs to land, large fortunes and stately homes. According to a source, she arrived "knowing no one and made it her business to leave knowing everyone."
Certainly, she shared a house with Lord Edward Innes-Ker, a son of the Duke of Roxburghe, and Earl Percy, heir to the Duke of Northumberland and therefore to Alnwick Castle, which stands in for Hogwarts in the Harry Potter movies.
For three years at university she dated a penniless tree surgeon … no, only joking, her beau was in fact Jonathan "JJ" Jardine Paterson, an heir to the Jardine Matheson Hong Kong banking fortune. She was also linked to Scottish aristocrat Billy More Nisbett and diamond heir Simon Youngman, but in 2010 got together with Alexander Guy Rushworth Loudon. The son of a former High Sheriff of Kent, Loudon has been a pal of Prince William's since they were at Eton, and played cricket for Warwickshire before becoming a banker.
Loudon and Pippa are thought to be pretty much engaged but have kept their relationship low-key to avoid upstaging Kate's royal romance. His Fulham home is close to her Chelsea flat and his parents have a stately pile in Kent, Olantigh Towers. Suitably rich, well-connected, handsome and posh, he is also thought to be handy enough to give Harry a spanking if he tries anything. Pippa is closer to Prince Harry's on-off girlfriend Chelsy Davy than Kate is.
Steve Hirsch, CEO of porn producer Vivid, has offered Pippa $5 million to star in a single sex scene in one of his movies. "As far as I am concerned, you were the star of the recent royal wedding," he wrote in a letter to Ms Middleton.
In 2008 Pippa was named Number One Society Singleton by Tatler magazine, ahead of countless supermodels, actresses, rock stars and celebrity spawn. Even ahead of Princess Eugenie.
She appeared regularly on "cool" lists, but Pippamania really ramped up and out of control after her appearance at her sister's wedding. The Middleton sit-upon instantly inspired admiring comments on Twitter from singer Justin Bieber, cricketer Michael Vaughan and Calum Best. Teenage Olympic diver Tom Daley joked he was going to marry her.
There are now several people pretending to be Pippa on Twitter, including @IamPippaM, which claims to be her official site but clearly isn't, @Pippa_Middleton and @PippathePauper. The first has 4,207 followers, the second and third 3,100 and 1,269. The Twitter feed @PippaMiddleton has 298 followers although it has not posted a single message. Another feed, pretending to represent Pippa's bottom, has 1,555 followers, and recently posted the message: "Is anyone else watching Lady Gaga concert? My bum is nicer." The Twitter feed for "Orlando", the comic toff student character whose "Gap Yah" sketch went viral last year, is currently tweeting that he is not seeing Pippa. Or Harry. Whatever the superinjunction leaks say.
There are at least 15 people pretending to be Pippa on Facebook, 20 Facebook groups dedicated to her derrière, and 50 suggesting that she should get together with Harry. More than 100 people have used Facebook's "check-in" function to claim they have checked in to Pippa's house, bedroom or underwear, and 211,747 have given her bum the thumbs up.
The most popular video of her rear view as she follows Kate into the Abbey, entitled Pippa Middleton Shake Ya Ass, had 521,757 hits on YouTube at time of writing.
The Middleton sisters reportedly share the services of a mobile tanner who sprays them with fake bake, and Pippa has her hair done in the VIP section of Richard Ward's Chelsea salon.
She works out with her sister in the gym at Clarence House, likes swimming and tennis, but has given up her youthful passion for hockey: a shiner from an ill-wielded stick wouldn't have looked good at the Abbey. As a spectator she's been seen at - big surprise! - Royal Ascot and Cartier Polo.
Fashion-wise, Pippa shares her sister's passion for knee-high boots but prefers them in suede. She also wears ballet pumps from French Sole, well-cut tweeds from Katherine Hooker, and frocks from Sonia Rykiel and Chloe if she's after something more vampy and colourful. On holiday, we now know, she favours a white bikini.