Royals Kate Middleton Used the Ultimate Mom Hack at George and Charlotte's Polo Playdate We've all been there! By Christina Butan Christina Butan Instagram Christina Butan has been working in media since she graduated SUNY Purchase in 2017 with a bachelor's degree in journalism and the Peter Keller Journalism Prize. She started out as an editorial assistant and news writer for PEOPLE, and then joined the Dotdash Meredith commerce team as an Amazon writer in 2019. She quickly became well-versed in commerce content and worked her way up to becoming a Senior Commerce Writer and Strategist for InStyle, where she pitches, writes, assigns, and edits stories covering celebrity style, beauty trends, editor's picks, and more. People Editorial Guidelines and Simon Perry Published on June 13, 2018 11:35 AM Share Tweet Pin Email One day after attending the Trooping the Colour celebrations, Kate and her older two kids, Prince George and Princess Charlotte, went to cheer on Prince William at his charity polo match in Gloucester, England. “Kate is a fantastic mum,” an onlooker at the match tells PEOPLE. “She was calm with the children.” Using a British phrase for “run loose,” the onlooker says, “She let them have their head.” The royal mom, 36, who welcomed son Prince Louis on April 23, also used a tried-and-true technique for planning the rest of her day. At one point, “She seemed to say to [George, 4, and Charlotte, 3], ‘First to the polo field is the winner!’ ” the observer adds. “She was trying to get them tired before they had to get back in the car to leave.” James Whatling/MEGA Kate watched the kids and rooted for her husband while wearing a casual striped blue sundress from Zara paired with 3-inch espadrille wedges (that she later ran in!). George and Charlotte also ran around the field and played with their older cousin Savannah Phillips, the 7-year-old daughter of William’s cousins Peter and Autumn Phillips. “[Savannah] sat with Charlotte in her lap,” says the observer. “She hugged her and balanced her on her knee.” RELATED VIDEO: How 3-Year-Old Princess Charlotte Took Charge of the Other Kids at the Royal Wedding: ‘No, You Can’t Go Yet!’ Charlotte also took notes from her older cousin as she attempted to do a headstand just like she did, which gave Kate a laugh. Samir Hussein/Samir Hussein/WireImage George didn’t participate in the headstand action, but did entertain himself by playing with a rainbow slinky. Karwai Tang/WireImage SplashNews.com Can’t get enough of PEOPLE’s Royals coverage? Sign up for our newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Despite the photographers, Kate “didn’t get stressed about it, or pass that along to the children,” says the onlooker. “She let them play. She let them get on with it, sliding down the hill and rolling on the grass.”