Charles Spencer on the royal fallout following Princess Diana's death

Charles Spencer is testing one of the lingering questions of our time: can the world ever get enough of his sister, Diana, Princess of Wales?

It turns out the controversy surrounding her life has not faded nearly 30 years after her tragic death.

In fact, Spencer's new book, "Swan Song: Diana, My Sister" (to be published Tuesday by Penguin Press), has pulled the scabs off some old wounds, especially when he recounts an unsettling conversion he says he had with Diana's ex-husband – now King Charles – shortly after she died: "He said about Diana, 'We'll forget her soon enough.' And he said it, I can't really recreate it, but it was said with a bit of a hiss, to be honest. And I said, 'I can't believe you said that.'"

You'd have to have been living under a rock not to know Diana's story … the daughter of one of England's grand aristocratic dynasties, chosen at just 19 to be the bride of the then-Prince Charles. Their seeming fairy-tale wedding, which turned into a rocky marriage, that ended in a bitter divorce. Her tragic early death in a Paris car crash. It was a riveting, if sad, real-life soap opera, with an apparently insatiable worldwide audience. 

But why do a new book about such a well-known story?

"With the 30th anniversary of her death coming up next year, I was getting inundated with requests to be in somebody else's book or documentary," Spencer said. "And it suddenly occurred to me, well, if you're all so interested in hearing from me, I might just give you the definitive story."

Well, the Spencer version of the story.

Diana has always divided opinion. She was the modern breath of fresh air who blew the cobwebs out of the fusty royals – or she was the upstart whose popularity threatened the old ways and undermined an institution that had done very nicely, thank you, by maintaining its aloofness and its mystery.

Asked what he believes people have gotten wrong about Diana, Spencer replied, "I think people who picked at her and found fault with her did so without a true appreciation of the unique force that she was."

Was it malice? "I think a lot of people in the British establishment didn't know what to do with this totally rogue but brilliant force," Spencer said. "And there were a lot of attempts during her time on the public stage where they tried to suppress her. Diana would call them the 'men in gray suits' – people working for the royal family in particular."

Charles Spencer is the 9th Earl Spencer. His family has not endured near the top of the British aristocratic food chain by being critical of the royal household, but Diana's story has changed that.

Speaking at Althorp, his family's estate, Spencer said, "We're sitting in a house here, surrounded by portraits of my ancestors, all of whom served the crown very loyally. And there was probably a thought when Diana was plucked to become a royal bride that she would fit into the mold of the past, and she didn't. And so, I don't know about malice, but I do know about jealousy.

"She said it was very difficult, even from her first royal tour overseas, which was to Australia, how if she was on one side of the street with the public and [Charles] was on the other, the crowd on his side of the street were less thrilled, and that this was very difficult for him," Spencer said.

And, of course, Charles' continuing connection during the marriage to his old flame, now Queen Camilla, didn't help.

King Charles does not come off well in this book. So badly, in fact that the palace has responded, saying Spencer's recollections may be the result of "fraternal grief that can cloud reason, affect judgement and colour memory." Memories like the one of a call Spencer says he got from Charles soon after Diana's death: "He sounded excited in a sort of upbeat way," Spencer recalled. "And obviously I'm not justifying or criticizing, I'm reporting that's the fact."

Spencer has suggested that Charles may have felt "upbeat" because he finally felt free to pursue Camilla. "I said that that might've been it, yeah. But that's obviously, I can't say what he was thinking, but I'm trying to think why would somebody feel giddy at that time."

"I stand before you today the representative of a family in grief"

In his eulogy at Diana's funeral in September 1997, Spencer cast himself as protector of her legacy, and of her children, particularly after they were made to walk behind their mother's coffin. "I thought it was such an absurd idea that I just thought, well, that won't happen," he said.

Because he felt it would be too hard on the boys? "That, and I thought it was barbaric," he replied.

Spencer said he believes the idea of having them follow their mother's coffin through the streets of London was to protect Charles from the crowd's reaction. "That's what I heard from politicians who were involved at the time, yes," he said. "There was a concern that if he walked alone behind Diana's coffin, that he would be insulted by people in the crowd. That was the fear. And that that couldn't possibly happen if the boys walked behind. I was told they wanted to do it. And I was, I believe I was lied to."

Asked if he had talked about it with his nephews, Spencer said, "I never discuss what I've discussed with William and Harry, but I know the truth from all angles, I can put it that way."

It's been a long time since Diana was buried on an island on the family estate. But to Charles Spencer, what happened back then is still having an effect now.

Asked if he thinks Harry's current difficulty with the family and the press harkens back to his experience of the time his mother died, Spencer replied, "I do sometimes wonder with the situation, if I can call it that ..."

Between Harry and William? "I think the broader one of Harry's feelings, I wonder how much it is connected to this very sad time," Spencer said. "He was so young. And I just wonder if a gentler, more understanding treatment of his grief then might have helped him, and that everyone might have found a happier course ahead."

Asked what kind of queen Diana would have made if the marriage had lasted and she had lived, Spencer replied, "I think Diana would have been a really amazing queen. To have a sort of superstar in that role would have been very good for Britain."

WEB EXCLUSIVE: Watch an extended interview with Charles Spencer (Video)

Read the full statement from Buckingham Palace:

"While we do not comment on books as a matter of principle, His Majesty is 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."

For more info:

• "Swan Song: Diana, My Sister" by Charles Spencer (Penguin Press), in Hardcover, Large Print Trade Paperback, eBook and Audio formats, available Sept. 22 via Amazon, Barnes & Noble and Bookshop.org

     
Story produced by Mikaela Bufano. Editor: Brian Robbins. 

See more: 

From 1997: The life and death of Princess Diana, hounded by paparazzi ("Sunday Morning")

From 2015: Charles Spencer on Diana, Althorp and the death of kings ("Sunday Morning")