When Prince Harry and Meghan stepped back as working royals, one of the conditions on which they forged their independent lives was that they would retain their HRH titles but not use them. Standing for His or Her Royal Highness, the styling is held by senior royals in lieu of their position within the monarchy.

Since it emerged that Meghan Markle sent a gift basket to a friend with a card that described her as 'HRH The Duchess of Sussex' controversy has grown - now a constitutional expert has weighed in