It is thought that the royal couple welcomed teenagers - Lily Rice, Junior Frood and Siena Castellon - into their home to praise them for their inspirational work after being crowned Teen Heroes of 2018.
Speaking to HELLO! after the meet-and-greet, 16-year-old Siena - who has supported other students with autism and learning difficulties - revealed: "It was such an honour and privilege to meet the Duke and Duchess of Cambridge at Kensington Palace.
They were both genuinely interested in my website,
www.QLMentoring.com, which I created to support and mentor autistic students and students with learning disabilities.
Of meeting the royals, she added: "The Duchess was especially interested in addressing autism stereotypes and was saddened to hear about the severity of the disability-related bullying I have experienced. She congratulated me for being a Diana Award holder and for currently serving on the National Youth Board, a role that has given me a national platform through which to share my disability-based bullying experience.
They were both incredibly warm, supportive and encouraging. Meeting them was an awesome experience! They have inspired me continue to make a positive difference in my community.”