Prince William, Camilla, and King Charles III
King Charles III is seen here with his successor Prince William and Queen Camilla as he is officially proclaimed Britain's new monarch. Photo: Reuters / POOL Reuters / POOL

King Charles III has reportedly set his succession plans in motion amid fears that his cancer could be more dangerous than what the public has been led to believe.

Buckingham Palace announced on Feb. 5 that the 75-year-old monarch has been diagnosed with cancer after undergoing prostate surgery. But the palace was scant on details, especially on the type of cancer and its severity. Although, according to reports it is not prostate cancer.

The palace said His Majesty wanted to share his diagnosis to help raise awareness about the disease and that he remains positive with his treatment. The King has been photographed in good spirits amid his cancer battle and recently resumed with his weekly audiences last week and met with U.K. Prime Minister Rishi Sunak.

But according to royal author Tom Quinn, despite his positive outlook, the cancer diagnosis still prompted King Charles III to formalise his succession plans and made sure that his eldest son, Prince William, is at the heart of it.

He told the Mirror: "Charles is also aware that, as future king, William is at the heart of the succession planning that is taking place right now – officials had assumed Charles would remain healthy at least into his mid-eighties before succession planning would need to begin but in fact it has now begun and indicates perhaps that Charles' cancer is more dangerous than we have been led to believe."

Quinn, who authored the 2023 book "Gilded Youth: An Intimate History of Growing Up in the Royal Family", claimed that King Charles III does not trust his youngest son, Prince Harry, not to divulge details to the media, so he is not part of the succession planning.

He said: "Succession planning is highly secret and no one trusts Harry to be part of it for the simple reason that if he feels in any way slighted or not given what he feels he deserves he will run straight to the media."

The author's statement comes after the Duke of Sussex talked about his return to the U.K. on Feb. 6 to see his father in an interview with "Good Morning America". He said he is "grateful" that he got to spend time with him but declined to share what transpired during their meeting.

As for the succession planning, Buckingham Palace has yet to corroborate Quinn's statements. King Charles III waited decades to ascend the throne and the public believes he would not give it up easily despite his cancer diagnosis.