"I was quite taken aback by her knowledge of photography," Hugo Rittson Thomas tells PEOPLE

By Monique Jessen
Updated May 18, 2016 01:05 PM
Credit: Arthur Edwards/Getty

Princess Kate‘s photographs of Prince George and Princess Charlotte have captivated fans around the world, and now they’ve been given the seal of approval – from the Queen’s portrait photographer, no less.

“I thought they were wonderful pictures, beautifully shot,” Hugo Rittson Thomas told PEOPLE at the London launch party of his latest book, The Queen’s People, on Tuesday night.

“She captured the joy, happiness and youth of her children which is a wonderful thing and sometimes hard to do as a parent,” Rittson Thomas says of the pictures Kate released to mark her children’s birthdays.

One of the U.K.’s most respected portrait photographers, Rittson Thomas has spent the last four years working on his striking new project, which features 42 portraits of the Queen and various members of the royal household.

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Although Kate is not featured in the book (she was pregnant with Prince George at the time), Rittson Thomas met her back in 2012 as he was getting ready to photograph Prince William.

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“I was quite taken aback by her knowledge of photography. She asked a lot of technical questions about what I was doing and the set up – she almost caught me out a few times actually!”

Kate, who studied art history at the University of St. Andrews in Scotland is a keen photographer who is often seen on royal tours clicking away on her Canon EOS 5D Mark II.

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“If circumstances had been different, she could definitely have had a career in photography – she has a lot of talent,” says Rittson Thomas.

Published by Assouline, the hand-bound limited edition book is available from May 24 and costs $845.