Prince William reveals how daughter Princess Charlotte tells everyone she is a teenager William also revealed that Charlotte had a "lovely day" celebrating her 6th birthday, and was joined by other members of the British royal family. May 6, 2021 11:22 BST Princess Charlotte had a lot of fun celebrating her 6th birthday over the weekend, but her favourite part of turning a year older has been pretending that she is now a teenager. During an outing on Tuesday, Prince William was asked about how his only daughter celebrated her special day on Sunday, May 2. Sharing the cheeky and playful side of the young princess, the Duke of Cambridge said she now says she is 16 whenever someone asks her how old she is.