The Queen and other senior royals wear tiaras at state banquets, for example, or when attending important events on royal tours.

As the daughter of a future king, Princess Charlotte may one day be a working member of the Royal Family.

Therefore, Charlotte could too be permitted to wear a tiara when attending formal events at the palace in the future, for example.

There is also a tradition that members of the Royal Family are lent a tiara by the Queen when they get married.