"I'm so happy that she chose our cardigan, first for Prince George and now for Princess Charlotte – it's so lovely and exciting to see our pieces enjoyed and worn in different ways," Amaia Arrieta, co-owner of the eponymous children's wear boutique, tells PEOPLE exclusively. "They all look amazing and seem to be having such a great time."
(PEOPLE takes you on an exclusive tour of the London boutique – and supplier of George's signature knee socks! – here.)
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