Prince Harry and Meghan Markle reportedly took a photo showing the line of succession to heart.

Prince Harry was reportedly upset by this image of the late Queen, William, George and Charles (Image: PA Images/Ranald Mackechnie)

Prince Harry and Meghan Markle were sent a message about the line of succession in a royal photo featuring King Charles, Prince William and Prince George, a royal author claimed.

The picture was issued in December 2019 and showed the late Queen Elizabeth II, King Charles, who was then Prince of Wales, Prince William and Prince George.

It caused some controversy, according to author Robert Lacey, who in his book Battle of Brothers claimed the snap was Charles’s idea and designed to show the then future monarch’s ambition for a slimmed down monarchy.

Mr Lacey, writing for the Daily Mail, described the image as “fascinating” and “historic”, reminding viewers of the “essence of the royal system”.

He added: “The (then) current monarch with three future monarchs. All the living heirs – and not a suggestion of a ‘spare’.”

Prince Harry and Meghan Markle took the photo ‘to heart’, Robert Lacey has claimed (Image: Getty)

The photo shows Elizabeth II standing between Prince William and Prince Charles, whose right hand rests on Prince George’s shoulder.

Mr Lacey, citing palace insiders, said the photo was taken in the Throne Room of Buckingham Palace a week before Christmas and Charles’s idea.

He added palace sources “let it be known” the plan to depict the direct line of royal succession was “enthusiastically supported” by William, which, according to Mr Lacey, “might be seen as sending his younger brother a message”.

The author claimed the Duke and Duchess of Sussex took the photo “to heart”, though other experts have said the decision probably wasn’t meant to upset the pair, but shows how the monarchy works.

ITV’s royal editor Chris Ship said the portrait was released to mark the start of the decade.

Prince William ‘enthusiastically supported’ plans for the photo, Mr Lacey claimed (Image: Getty)

He said: “It was the Queen and the three future kings – and there was also a bit of video of them stirring Christmas puddings.

“I’m not saying they were cutting Harry and Meghan out because it was a brutal fact that Harry was never part of that line of succession.”

Mr Ship argued that with the image it felt as if the Royal Family was focusing on the future, with the Queen and her three heirs.

Succession to the throne in Britain is regulated through descent and Parliamentary statute. Prince William is next in line to the throne, followed by Prince George, Princess Charlotte and Prince Louis.

Prince Harry is fifth in line to the throne, while his son Prince Archie is sixth in line, and daughter Princess Lilibet is seventh.

Kensington Palace has been approached for comment.