Harry, born a prince of Wales, has been styled an HRH since birth and was given the title the Duke of Sussex by his grandmother the Queen on the morning of his wedding.
American former actress Meghan Markle became HRH the Duchess of Sussex after saying her vows.
In the Queen’s statement sanctioning their new life, the monarch refers to the couple not at first by their official titles.
Instead, with an unusual degree of informality for the monarch, she calls them “Harry and Meghan”, only later on in the statement referring to them as the Sussexes.
This has been taken as a clue as to what might be in store, with commentators questioning whether there is the prospect of the couple losing their HRH style and even their royal titles.
Their son Archie Mountbatten-Windsor is not an HRH nor a prince as he is too far down the line of succession from the monarch.
Harry and Meghan could have used the courtesy title Earl of Dumbarton for him, or he was entitled to be Lord Archie Mountbatten-Windsor.
But they took the personal decision to make him a plain Master, most likely inspired by Harry’s wish to have been a normal child, rather than a prince, as he grew up.
Archie will, however, be entitled to be HRH and a prince when the Prince of Wales accedes to the throne – although it is not thought likely Harry and Meghan would opt for this.
After their bombshell statement last week, bookmakers Ladbrokes cut the odds from 5/1 to 5/6 that the Sussexes would relinquish being HRHs.
Harry’s mother was stripped of her HRH style and her title the Princess of Wales becoming Diana, Princess of Wales following her divorce from the Prince of Wales in 1996.
The Duke of York’s ex-wife who was HRH the Duchess of York became Sarah, Duchess of York after they split.
The abdicated Edward VIII became the Duke of Windsor and finally married American divorcee Wallis Simpson while in exile in France in 1937, and none of the royal family attended.
But he kept his HRH style.
A Letters Patent by his brother the new King George VI decreed that Edward “having been born in the lineal succession to the Crown” should be “entitled to hold and enjoy for himself only the style title or attribute of Royal Highness”.
Mrs Simpson became the Duchess of Windsor but was never permitted to adopt the style of an HRH, with George VI’s Letters Patent forbidding it.