Next stop Manhattan!

It's a subject that for the past week has been generating no (rear) end of conversation among Big Apple-based Brits: Will Pippa Middleton — the party-loving, pert-posterior-owning younger sister of future Queen Kate — be making her home in New York?

Ever since she notoriously stole the show from her big sister at the royal wedding in April 2010, Pippa, 28, has been a star in her own right. She’s secured an advance of nearly $650,000 from Penguin for a book on the art of party planning, which is scheduled to be released in the fall, and split up with boyfriend Alex Loudon — who accompanied her to her sister’s wedding. And last month, she caused a scandal when she was photographed in an Audi in Paris, seated next to a pistol-packing French playboy named Arthur de Soultrait (who later apologized for waving the weapon, which he insisted was a toy gun).

The word in London is that Pippa is getting tired of being endlessly scrutinized under a British lens, and is thinking of moving to New York to escape the strain of living in her sister’s shadow. A friend of Pippa, who lives and works in New York and spoke to The Post on condition of anonymity, confirmed that Pippa was considering a move to the city that never sleeps.

“She’s at a crossroads in her life — single and ready both for a fresh career challenge and to embrace a new scene,” says the source.

“Moving to New York is something she’s contemplating — but it’s far too premature to think she’s sitting at home, on the Kayak Web site, about to purchase a one-way ticket to JFK.”

But it won’t be her decision alone.

“The Middletons are a particularly close family and even though she’s a senior royal, Kate still depends on her in all sorts of ways. A move to New York is almost as much Kate’s decision as it is Pippa’s,” the source says.

“If Kate ultimately finds her sister is indispensable, Pippa will end up in London. Their younger brother James can make a mean cupcake, but it’s doubtful he can effectively serve the interests of the Middleton family as well as his sister.”

Pippa will be spending a time in New York to promote her book, “Celebrate,” in the fall, and it’s thought she’ll make a definitive decision on her long-term plans when she’s over here.

“She’s certainly not short of friends in New York,” the pal says, citing p.r. maven Georgie Downie — who, like Pippa, is an ambassador for the Too Many Women cancer charity — and family members of her ex-boyfriend Loudon, who live here and with whom Pippa is close.

Insiders say her set in the city would also include video journalist Willem Marx, sister Kate’s ex-boyfriend from Marlborough College, and Luke Parker Bowles, Camilla’s nephew.