THEY call them the Wisteria Sisters – highly decorative, terribly fragrant and with a ferocious ability to climb. But for Kate and Pippa Middleton, the question of who is the higher climber in society may be about to change. This week, Tatler magazine – bible for the huntin', shootin', fishin' and partyin' British aristocracy – named 23-year-old Pippa as the most eligible person in Britain on its annual hot list.
It's something of a coup for a young woman who is famous for being the sister of the girlfriend of the future heir to the throne (are you still following?). With her long, dark, glossy hair, willowy figure and delicate facial features, she is the spit of her older sibling. Unlike her sister, however, she has a full-time job, albeit one as a party planner with an upscale London catering firm called Table Talk. Tatler clearly thought this was a detail worthy of disdain, remarking that she "goes to a lot of parties, but mainly as the caterer". Ouch.
Still, thanks to the Middleton family's much discussed middle-class status, there is an element of proletarian revenge in Pippa's accolade. Indeed, there must be some wincing within the Royal household that, while Pippa Middleton makes it to number one on Tatler's list and Pixie Geldof, spawn of Bob Geldof and Paula Yates, makes it to number four, the Queen's granddaughter Princess Eugenie only just scrapes in at number 10. Double ouch.
But class differences aside, why all the fuss over Pippa? She is the middle Middleton (there is also a brother, 21-year-old James) and is, it is said, more outgoing and "sparkly" than her demure sister.
She is also a graduate of Edinburgh University, where she shared a flat with Ted Innes-Ker, son of the Duke of Roxburghe, and George Percy, son of the Duke of Northumberland, and where, apparently, she first started her determined social ascent.
"As soon as Pippa arrived at Edinburgh, she was assiduous about joining the right social circle," one university source claimed earlier this year. "She was very charming about it, but quite ruthless in cultivating the 'right' friends.
"If she found out that someone had impressive social credentials – the right title, standing, connections – she would immediately pay them a lot of attention, whereas before she wouldn't have shown the least interest."
It was at Edinburgh, where she studied English literature, that she met and for three years dated JJ Jardine Paterson, the son of a prominent Hong Kong banking family, and with whom she broke up around the same time as the much-publicised, albeit temporary, split between Kate and Prince William in April last year.
Newly single, the Middleton sisters hit the London social scene in style, turning up to nightclub openings and book launches, flaunting their coltish limbs and flashing their pearly white smiles for the cameras, a move that thrust the younger Middleton sister into the limelight for the first time. It was a role she clearly relished.
But while the sisters appear close – they are often pictured holding hands and currently share a flat in Chelsea (although Kate is rumoured to spend most of her time nowadays at Clarence House) – there is, allegedly, some jealousy between the pair.
One family friend was reported as saying earlier this year: "Kate was always quite jealous of Pippa. I sensed that she feared being eclipsed by her, because Pippa has more natural effervescence, is socially much more at ease and was always popular with everyone, especially James's friends.
"The two sisters are certainly close, but there was always a real sense of rivalry between them. Probably still is."
Perhaps it is not surprising, as studies and anecdotal evidence have shown that eldest children often feel a sense of jealousy towards their younger siblings.
Agony aunt Anita Naik says: "First children have a lot of expectations put on them, they're expected to be much more responsible and, because their parents expect so much from them, that can lead to a real perfectionist streak and a need to be accepted.
"Younger siblings have a lot more freedom. It's much easier to follow in a sibling's footsteps: you're never alone, you've got a path set out for you at school and you're not always in the company of adults. It can lead to jealousy. An older sibling will often think, 'That's not fair. I didn't get it that easy'."
Whatever the relationship between the sisters, it's clear they both have their sights set high. And if it's her older sibling's footsteps that Pippa is determined to follow in, then perhaps Chelsey Davy had better watch out.