Archie and Lilybet they were officially recognized as Prince and Princess by King Charles. Buckingham Palace has also updated the official website with the titles of the two children, while their order of succession to the throne is also displayed.

This came shortly after their parents – who live in California – said it was their “hereditary right” in a new statement defending their decision.

The Duke and Duchess also insisted the matter had been “settled a long time ago” with King Charles, despite it only being revealed by the couple yesterday. King Charles is said to have told Prince Harry that his children could be called a prince and princess in a private conversation after the Queen’s funeral last year.

A spokesman for Harry and Meghan said: “The children’s titles have been a hereditary right since their grandfather became monarch. This matter has been settled for some time in consultation with Buckingham Palace.”

However, their 21-month-old daughter Lilybet saw the royal title of ‘princess’ officially used when the couple announced she was christened in California without Charles, Camilla, William and Kate in attendance.

Sources close to the Sussexes have said they were disappointed that the Palace did not immediately recognize the children’s titles after the Queen’s death six months ago, as the “Daily Mail” writes. The Prince and Princess of Wales, as well as their three children, quickly changed their titles when Charles ascended the throne in September.

But Archie and Lily’s titles didn’t change until about 24 hours after the christening was announced. Buckingham Palace sources claimed they were waiting for Harry and Meghan to make the final decision.

The fact that King Charles did not block it – despite the upheaval caused by Harry and Meghan – is seen as a compromise move between them, according to reports. Royal sources said Charles would never “punish” his grandchildren in this way.

It is understood that despite the Sussexes’ repeated attacks on the institution of the monarchy and members of the royal family, there has been correspondence on the matter between the Duke and Duchess of Sussex and royal aides.

Harry and Meghan are understandably keen not to deny their children their right to inherit, but will give them the opportunity to decide for themselves when they grow up whether they want to give up or continue using the titles.

The christening of their youngest daughter came just days after King Charles evicted the couple from Elizabeth’s home in Britain, Frogmore Cottage. However, he has invited them to his coronation ceremony, which is scheduled for early May, but it is not yet known if they will attend.