A royal expert accused Prince Harry of stirring questions about the health of royal family members after he allegedly exposed King Charles III's secret battle with neck and back pains.

Daniela Elser called the revelation "a worrying pattern for the royals" because now the public would want to know about the royal family members' health woes. She referenced a passage in the Duke of Sussex's memoir "Spare," in which he talked about his father's "constant pain."

In it, the 38-year-old recalled spending time at Balmoral, King Charles III's private Scottish residence, and trying to find his way around the massive property with its 50 bedrooms.

He wrote, "Open the wrong door and you might burst in on Pa while his valet was helping him dress. Worse, you might blunder in as he was doing his headstands. Prescribed by his physio, these exercises were the only effective remedy for the constant pain in Pa's neck and back. Old polo injuries, mostly." Elser claimed that this passage in the book clearly proves that Buckingham Palace "has not been entirely upfront about just how fit the king might be."

Writing for News.com.au she explained, "Never before has there ever been any suggestion that the unflagging Charles might have been in 'constant pain' for all the decades that he was undertaking hundreds of engagements annually, serving as patron of more than 420 organisations and running the Prince's Trust."

In 2000, King Charles III suffered a terrible fall during a polo game with Prince William and Prince Harry. At that time, the British press only reported that he "hurt" himself after taking a "tumble" and was rushed to the hospital. There was an impression that it was not serious. But in 2006, His Majesty interjected some humour when he admitted during an interview that he was "quietly dying" from the accident.

Prince Harry has now shared in "Spare" the gravity of the pain that King Charles III has to endure from that polo accident. Elser noted, "The obvious question here is if we didn't know about this 'constant pain' situation, what other royal health problems might we not know about?"

Britain's Prince Harry's autobiography 'Spare' displayed at Waterstones bookstore, in London
Britain's Prince Harry's autobiography 'Spare' displayed at Waterstones bookstore, in London Reuters