Princess Charlotte is celebrating her 11th birthday today, and will no doubt have plans to mark the day with family and friends. While the young princess is one of the most famous children in the world, much of her life is kept private by her parents, Prince William and Princess Catherine, including her daily routines and school life.

Although they occasionally share facts about their only daughter, including the sports she likes, and let her step out on the royal stage for big events, the rest of the time they protect her privacy, as they also do with their two sons, Prince George and Prince Louis. This protection of her privacy was also held in the first few hours after she was born back in 2015.

After welcoming their daughter into the world on May 2, 2015, at 8.34 am, the Prince and Princess of Wales - who were the Duke and Duchess of Cambridge at the time - wanted to spend the first few hours of their princess's life enjoying the moment as a family before announcing the news later that same day.

However, these precious few hours without the world knowing about Charlotte were almost spoilt by one of their own staff members.

This is because former royal aide Jason Knauf had a note about the princess's arrival before it was publicly announced, and lost this note in the middle of London.

In an interview with 60 Minutes Australia, Knauf said: "We weren't going to announce it for another couple of hours, and I had this piece of paper to go write this press release.

"I'm still out there with hundreds of journalists trying to have a game face, and then I couldn't find the piece of paper, and I think I had dropped it somewhere on the street. Which we managed to get through, but not announce it."

He continued: "But somewhere on that street the entire time was a piece of paper that said there had been a little princess born, at what time and how much she weighed."

Knauf "never found" the paper; he said no one else did either, which meant the birth announcement was not leaked.

Princess Charlotte's birth was announced the same day she was born.

Prince William and Princess Catherine also showed their daughter to the world just hours after her birth as they stepped outside of the Lindo Wing of St Mary's Hospital.