When several London children and their mentors planned a small Christmas tea party, it’s safe to say they did not have a visit from Princess Kate on their bingo card. But, alas, when it comes to events that celebrate the achievements of young people and the adults who inspire them, there is no better person than the princess to make a surprise appearance.

Last month in London, the Princess of Wales snuck through the side door of a Christmas celebration to greet three adults working in childcare—a music therapist named Ray, a retired mental health nurse named Brenda, and a soccer coach named Russell—and the kids they’ve positively impacted.

Princess Kate took to Instagram on Saturday to share heartwarming photos of her attendance. In the images, the princess looks positively festive in her favorite holiday cardigan: a knit cashmere sweater by Miu Miu that features a black and white rose pattern, delicate pearl buttons, and a white collar and cuffs. She paired the cheery top with matching trousers and gorgeous white stud earrings. As for hair and makeup, she wore her brunette locks down and straight and kept her glam natural.

The princess beams as she holds Brenda’s hand and listens to the children and adults discuss how they’ve influenced each other’s lives. The princess later gave the children gifts.

“Three inspiring people making a real difference to the lives of young people,” Princess Kate captioned the post. “It was so lovely to join Rico, Arwyen, Jenson, Poppy, Henry and George for a special surprise celebration for the people in their lives who have helped shape them. Russell, Ray and Brenda, it was a pleasure to meet you!”

The tea party will appear in Royal Carols: Together At Christmas, the broadcast of her third carol service at Westminster Abbey, which took place on December 8. The Princess of Wales dedicated the carol service to all those who support and uplift children. She took time to recognize her inspiring guests in attendance, including midwives, health visitors, nursery teachers, and baby bank volunteers, and their dedication to the cause.

The service and surprise visit are linked to Princess Kate’s Shaping Us campaign, which aims to raise awareness about the developmental and social significance of a child’s early years.

“Only by valuing and supporting the vital role of the adults in a child’s world can we hope to make a difference,” she said in her special introduction of the broadcast.

Royal Carols: Together at Christmas will air today at 7:45pm on ITV1 and ITVX in the U.K.