Diana died aged 36 in a 1997 Paris car crash as photographers pursued her on motorbikes, sparking an outpouring of grief and a reckoning over whether the media bore some responsibility after it splashed details of her life across front pages for years.
Charles Spencer was speaking as he prepared to publish his book about Diana, which has been highly critical of her former husband, the now-King Charles, and after Harry and Meghan returned to live in Britain six years after they quit royal duties and moved to the US.
"From a security aspect, as an uncle who's seen his sister die in very, very preventable circumstances, I would veer towards protection," Spencer told the BBC, citing Harry's position as fifth-in-line to the British throne and as a former soldier.
He said the tabloid treatment of both Diana, and Harry and Meghan, could be "really, really unpleasant", that it was "beholden on people" to learn from that experience.
Spencer's book: Swan Song: Diana, My Sister, has made headlines around the world.
Spencer accused the then-Prince of Wales, of sounding "giddily elated" in the hours after her death and said an angry Charles had told Spencer that the world would forget Diana soon enough.
The palace hit back by saying the King was "mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss".
Asked by the BBC how he could prove the conversations had taken place, Spencer said he had included a specific line in his much-lauded eulogy at Diana's funeral to counter the comments, ending it by saying she would "never be extinguished from our minds".
Spencer said he had written the book, ahead of the 30th anniversary of her death, to celebrate her life. He said their childhood had never had a dull moment: "We both have ADHD. She was never diagnosed, but clearly we did".
Diana's family accused the royals of showing a lack of support or care towards the princess before her death, a charge that was repeated by Harry and Meghan before they quit royal duties in 2020 to move abroad.
Harry has criticised the government's decision to strip him and his family of automatic police protection afforded to other senior royals, after he quit royal duties. Following a long-running legal battle, that is now under review.
Spencer said his revelations would not come as a surprise to Harry or Prince William, and said while he knew many more details about the King he had chosen not to include them.
