So much for "Perfect Pippa."

Kate Middleton's younger sister -- who narrowly won the title of "Rear of the Year" in England -- is being accused of stuffing her Sarah Burton bridesmaid gown in order to give her tush a push for the Royal Wedding.

An "expert" who was called upon for TLC's "Crazy About Pippa" special questioned whether Pippa, 27, added some extra adding under her dress.

"I'm not convinced that it's completely natural," said London spa owner Lesley Reynolds Kahn. "Because I think, if you look at other photos of her and you see her in jeans, she's got quite a flat bottom.

But I think possibly for the day, for that gorgeous dress, she may have had some sort of pants that gave her a little bit of a lift, or even a little bit of padding."

If that's the case, then so much for the "Pippa Butt Lift" that women all over the world have been ordering from plastic surgeons.

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