The doting aunt picked up pink bloomers and more for her royal sister's new daughter

By Monique Jessen
Updated June 12, 2015 12:30 PM
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David M. Benett/Getty; Inset:HRH The Duchess of Cambridge/Getty

Add pink bloomers to the list of adorable gifts 6-week-old Princess Charlotte has received – this time, from her auntie Pippa.

Princess Kate‘s younger sister, Pippa Middleton, has helped stock Charlotte’s layette, and PEOPLE has all the exclusive details.

Knowing her sister so well, Pippa, 31, stopped off at one of Kate’s favorite children’s wear boutiques: Amaia in London’s Chelsea Green neighborhood. The shop has recently gained international renown for its selection of traditional English clothing for children – especially Prince George’s signature knee socks.

(Super-stylish toddler Harper Beckham is also a regular customer.)

The doting aunt bought a Liberty print pink top with bloomers in a matching fabric and a cardigan, PEOPLE has learned.

She also bought a blouse with a frilly collar similar to the one she wears in her official portraits.

Middleton – who recently unveiled several of her own designs for charity – chose the three-month size, which is the smallest size in Amaia stock, and remarked that she hadn’t shopped sooner because her sister and brother-in-law didn’t know whether they were expecting a little boy or girl.

RELATED VIDEO: Why Princess Charlotte Is the Perfect Baby!

As for those $11 knee socks, which are available in 15 different colors – George has four! – the shop is struggling to keep up with demand.

“It was crazy busy this weekend after he wore them again and the socks are continuing to sell out,” says shop co-owner Amaia Arrieta, “but luckily we can restock them quickly.”

For behind-the-scenes details on the new royal portraits and the family’s first month at home since Charlotte’s arrival, pick up this week’s issue of PEOPLE, on newsstands Friday

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