Do I believe the claims Charles Spencer made in his book? Yes, I do. My reasoning is that Spencer cannot afford to hurt his reputation as an historian. He's written some good books, including books covering aspects of the English Civil War. Given his aristocratic rank, he tends to side with the Cavaliers, but his work is important nonetheless. It's got to be hard work constantly writing about the losers of the wars. That's right, the Roundheads won, get over it.
Given his training, I very much doubt that Spencer would make up details about what, exactly, Prince Charles said about his former wife shortly after her death.
Having said that, I also believe we are now seeing a concerted campaign to have Charles abdicate, and hand the throne to his eldest son, William. Who is doing what, and for what reason, is unclear at this stage; is Prince Harry part of it, or just an irritant? Or is William conspiring with Spencer to undermine his father?
It's an interesting distraction from war in Ukraine and an ever more powerful Russia, Iran controlling the Strait of Hormuz, Houthis controlling access to the Red Sea, Saudi Arabia about to go bankrupt, and now Denmark surrendering and effectively handing over Greenland.
Earl Spencer has doubled down on his bombshell claim that King Charles said of Diana, Princess of Wales, “rest assured, we’ll forget her soon enough” days after her death, saying he is telling the truth.