Princess Kate follows in Queen Elizabeth's footsteps at royal engagement

Kate, 35, is now royal patron of Action for Children.

Kate was "incredibly proud" to be taking on the new role with Action for Children, according to a Kensington Palace spokesman.

Kate told her young admirers, "George and Charlotte would have loved to have met you."

Kate's second stop of the day was to the Caerphilly Family Intervention Team which works with young people struggling with emotional and behavioral issues.

"The Duchess firmly believes that every child who needs it should be given the best support at the earliest opportunity," a Kensington Palace spokesman told ABC News. "The Duchess is pleased to support Action for Children's important work. She is looking forward to getting to know the people that make Action for Children such a success and meeting the young people they work with."

William, Kate and Harry have chosen to tackle the often-taboo subject of mental health and encourage young people and families to speak up and speak out.