Montecito, California - Prince Harry and Meghan Markle have begun to use the titles "Prince" and "Princess" for their children Archie and Lilibet.

The Duke and Duchess of Sussex's youngsters became a prince and princess when their grandfather King Charles acceded to the throne, but have remained a plain "Master" and "Miss" on the Buckingham Palace website for the past six months.

The Palace confirmed the site’s line of succession list will now be updated to reflect the change after a spokesperson for the Sussexes publicly referred to Lili as a princess for the first time on Wednesday when announcing news of her christening.

It is understood the King was aware beforehand that the Sussexes intended to refer to their daughter as Princess Lili and that there had been correspondence about the matter.

Lili, who turns two in June, was baptized in California on Friday, with the couple’s spokesperson saying: "I can confirm that Princess Lilibet Diana was christened on Friday March 3 by the Archbishop of Los Angeles, the Rev John Taylor."

According to People, the couple invited King Charles, Queen Camilla, Prince William, and Kate Middleton, but they did not attend. A source said there were between 20-30 guests at the event, including Meghan's mother and Lilibet's godfather Tyler Perry, who brought a 10-person gospel choir to perform.

It is understood the titles will be used for the couple's kids in formal settings, but not in everyday conversational use by the couple, and this was the first opportunity to do so since the death of the late Queen.

Harry and Meghan are understood to not want to deny their children their birthright, but to allow them the chance to decide for themselves when they are older whether to drop or keep using the titles.

The use of the titles has been revealed just days after Harry and Meghan were asked to vacate their UK home Frogmore Cottage, a move sanctioned by the King which further weakens the couple’s ties with Harry’s home country and the Windsors.

The past few months have seen huge turbulence in Harry and Meghan’s relationship with Charles and other members of the royal family.

Harry, who stepped down as a senior working royal in 2020 for a new life in the US, criticized his father’s parenting in his controversial autobiography Spare, accused the Prince of Wales of physically attacking him and said the Queen Consort sacrificed him on her own personal PR altar.

The duke and Meghan, in their bombshell six-part tell-all Netflix documentary series, also claimed Kensington Palace lied to protect William when it issued a statement denying a story he had bullied Harry out of the royal family.

Title rules set out by King George V in 1917 mean Archie and Lili, as the children of a son of a sovereign, automatically became a prince and a princess when Charles became King.

They would also be entitled to an HRH style, but although Harry and Meghan retain their HRH styles, they no longer use them after quitting the working monarchy.

Meghan said in the couple’s interview with host Oprah Winfrey that Archie was not given the title of prince because of his race.

However, when Archie was born seventh in line to the throne in May 2019, he was too far down the line of succession. Although he was a great-grandchild of the monarch, he was not a first-born son of a future king, so was not automatically a prince.

It was previously reported in 2021 that Charles, in a bid to limit the number of key royals, intended, when he became monarch, to prevent Archie becoming a prince.

To do so, he would have to issue a Letters Patent amending Archie’s right to be a prince and Lili’s right to be a princess.

The Sussexes have yet to confirm whether they will attend the King’s coronation in May, which falls on Archie’s fourth birthday.