Aaron Chown/pool photo via AP In British nobility, you are automatically a prince or princess at birth if you are born to a sitting monarch, are born to the eldest son of a sitting monarch, or are otherwise declared to be so by a sitting monarch. Since Prince Harry is not the eldest son of the Prince of Wales, any of his children will officially be Lord or Lady Mountbatten-Windsor at birth — according to current rules. Sitting monarchs can issue Letters Patents, which can change the titles and styles of members of the royal family for the term of that monarch’s reign, but are not considered Acts of Parliament and do not change the law for future generations. Following the lines of British nobility can be confusing — that's one of the reasons Debrett's of London exists. As you might already know, upon marrying Prince Harry, the Queen officially bestowed a few titles on Meghan.