Royals Kate Middleton Says 3-Year-Old Son Prince Louis Is 'Very Quick' on His Scooter: 'I Can't Keep Up!' Kate spoke about her youngest child during a phone call with a young girl named Mila who knew all of Kate and Prince William's children's names By Stephanie Petit Stephanie Petit Stephanie Petit is a Royals Writer/Reporter at PEOPLE. She has been with the brand since 2016 after graduating from The College of New Jersey and holding previous positions at Seventeen, CBS Radio and more. Follow the proud dog mom on Twitter at @stephpetit_ for the latest on Queen Elizabeth's corgis. People Editorial Guidelines Published on May 6, 2021 01:05 PM Share Tweet Pin Email Prince Louis and Kate Middleton. Photo: Will Warr Prince Louis is keeping mom Kate Middleton on her toes! In honor of the publication of Hold Still: A Portrait of Our Nation in 2020 on Friday, Kensington Palace shared Kate's August phone call with 4-year-old Mila, who appeared in the image "Shielding Mila" and had to isolate away from her father and big sister last year while she was receiving chemotherapy for acute lymphoblastic leukemia. After greeting Kate by saying, "Good morning, Your Royal Highness," Mila revealed her royal knowledge goes beyond etiquette. "I know all your kids' names," Mila told Kate during the chat. "Do you?" Kate replied. "What are their names — can you remember?" Mila correctly identified Prince George, Princess Charlotte and Prince Louis, to which Kate gave an impressed cheer. Royal Family Shares Never-Before-Seen Photos of Prince Philip with George, Charlotte and Louis! Kate went on to talk about her youngest child, who celebrated his third birthday on April 23. "Louis has gotten so big now — he's very quick running around," the royal mom said. "And he's on his little scooter as well. He's very quick. I can't keep up with him!" Get the premiere issue of PEOPLE Royals for glamorous new photos and inside stories royals fans haven't seen or read elsewhere! Subscribe at peopleroyals.com/launch Mila shared that she also liked to play on her scooter, but she said her favorite activity was walking her dog, Mr. Cole. Kate was seen chasing after Prince Louis in a rare video showing life at home with the Cambridge family that was shared in honor of Kate and Prince William's 10th wedding anniversary last week. And in a photo (taken by Kate!) celebrating Prince Louis's birthday and first day of nursery school, he gives a big grin to the camera as he poses on his red walker bike. In addition to speaking about the poignant photograph, Mila had a big question to ask the Duchess of Cambridge: "Do you have a costume?" "I'm not wearing a princess costume right now, I'm afraid, Mila," Kate said. After learning that Mila liked to play dress-up and that her favorite color was pink, Kate made her a promise: "I have to make sure I go and try to find myself a pink dress. Hopefully, when one day, hopefully, Mila, we'll get to meet, and then I'll remember to wear my pink dress for you." "Yay!" an excited Mila exclaimed. "Would that be nice?" Kate said. Princess Charlotte Tells Everyone She's 16 — Not 6, Says Prince William More conversations between Kate and Hold Still participants are set to be released in coming weeks. Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Launched by the Duchess of Cambridge in May, Hold Still invited people of all ages to send in a portrait that they had taken during lockdown in an effort to capture the story of the people at this unique and challenging time. "We've all been struck by some of the incredible images we've seen which have given us an insight into the experiences and stories of people across the country," Kate said in a statement at the time. "Some desperately sad images showing the human tragedy of this pandemic and other uplifting pictures showing people coming together to support those more vulnerable."