It was announced in the media today that Her Majesty The Queen has issued special Letters Patent that will ensure that, regardless of the gender of Baby Cambridge, he/she will carry the title Prince or Princess and be styled a Royal Highness.
Without this move, a female Baby Cambridge would only have carried the title “Lady,” based on Letters Patent issued in November 1917 by King George V which stated: “the children of any Sovereign of these Realms 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.” A female Baby Cambridge would be the eldest daughter of the eldest son of the Prince of Wales.
This most recent action by the Queen does not change the fact that the title of Prince/Princess and style of Royal Highness is restricted to the children of the Sovereign’s sons. It is for this reason that of the Queen’s Kent, Gloucester, and Harewood Royal first cousins, only the Kents and Gloucesters are Princes/Princess and carry the style His/Her Royal Highness (these include the Duke of Kent, Prince Michael of Kent, Princess Alexandra (all three pictured below), and the Duke of Gloucester).
The Queen’s Harewood cousins, the late Earl of Harewood and his younger brother, the late Gerald Lascelles, did not enjoy any such styles and titles, as they were the children of Princess Mary, The Princess Royal, the only daughter of King George V and Queen Mary (the Harewood wedding photo is below).
This particular rule also applies to the children of the Princess Royal, Peter and Zara Phillips – had they been children of a son of the Queen, they would have been Prince Peter and Princess Zara and carried the style His and Her Royal Highness. It is believed that, before Peter’s birth, the Queen offered to raise Mark to the Peerage (as she had done for Antony Armstrong-Jones – Princess Margaret’s husband) so that Peter would have be born with the type of courtesy title given to children of Peers of the Realm, but that the couple refused the offers. Thus, Peter and Zara have always been Mr. and Miss/Ms.
This move, like the legislation being introduced to change the rules of succession, is illustrative of efforts to modernise the Monarchy. There are those who have concerns about such changes being made in haste (including, accordingly to the British press, the Prince of Wales) because there is a concern that there may be consequences of which not everyone has not thought.