On 4 June 2021, the Duchess of Sussex gave birth to a daughter named Lilibet “Lili” Diana Mountbatten-Windsor. So is Lili entitled to a title?
The 1917 Letters Patent state “It is declared by the Letters Patent that the children of any Sovereign of the United Kingdom and the children of the sons of any such Sovereign and the eldest living son of the eldest son of the Prince of Wales shall have and at all times hold and enjoy the style, title or attribute of Royal Highness with their titular dignity of Prince or Princess prefixed to their respective Christian names or with their other titles of honour.” This was amended to include all the children of the eldest son of the Prince of Wales (namely The Duke of Cambridge’s children, George, Charlotte and Louis), mainly because if George had been born a girl, she would have been “Lady” rather “Princess,” while changes to make the succession gender neutral were already underway.1
Therefore, Lili (and Archie, too) does not fall under the 1917 Letters Patent, which would have allowed them the HRH and Prince(ss) in front of their Christian names. This would only happen when Charles succeeds as King because then they would both be “children of the sons of any such sovereign.” However, as children of a Duke, they are still entitled to courtesy titles. Traditionally, the eldest son and heir of a peer holds a subsidiary title of their father as a courtesy. This means that Archie is entitled to be styled as Earl of Dumbarton. Any daughters of a Duke are to be styled as “Lady,” which means that Lili is entitled to be called “Lady Lili.”
It seems that the Duke and Duchess of Sussex have decided to forego any courtesy titles for Archie, so it seems likely that they won’t be using Lili’s either. However, she is entitled to it, just as much as she will be entitled to be styled as HRH Princess Lili of Sussex when her grandfather becomes King.