EXCLUSIVE: Princess Diana Fans Unleash Furious Backlash Against Charles Spencer's Explosive Book

Princess Diana fans have unleashed a furious backlash against Charles Spencer's explosive new book about his sister, RadarOnline.com can reveal – as one prominent collector accused people of repeatedly trying to "cash in" on the late princess.

Renae Plant, 55, who has spent millions acquiring items connected to Diana and is preparing to exhibit 750 of her possessions in California, has criticized Spencer, 62, over Swan Song: Diana, My Sister.

The Los Angeles-based mother of three has followed Diana since watching her 1981 wedding and met the princess during a royal visit to Australia two years later.

A source familiar with the reaction among Diana admirers claimed, "Renae is only one of an army of Diana and royal fans who are outraged by the book and some of the claims Charles Spencer has made.

"There is a feeling among them that Diana's story has been picked over endlessly for nearly three decades and that every new revelation inevitably opens old wounds and creates another controversy around her.

"Charles was Diana's brother and obviously has every right to tell his own story and describe events as he remembers them. But some of her admirers are questioning whether publishing intensely personal material genuinely protects the sister he says he loved."

The source added, "These fans have followed Diana's life and legacy for decades. They are extremely protective of her memory, and the reaction to the book reflects how strongly people still feel about her."

Plant, who has not yet read Spencer's book, said: "People always cash in on Diana, and I hate it."

She was also quoted by the Daily Mirror adding: "To keep bringing up these pieces that are going to sell a book when you're telling people you're never going to cash in on your sister is kind of contradictory to me."

Plant also noted: "It doesn't sit well with me. If you want to protect your sister, you don't go and talk about her in a way that's going to stir everything up again to make it negative."

She was also surprised Buckingham Palace responded publicly to claims surrounding the memoir.

"I was quite shocked when the King commented on it," she confessed.

She added: "That they commented means they're very upset about what's been said. They commented before the book was even released – that's how worried they were about it."

Plant, who owns a preschool with her husband of 24 years, Livinio, has also criticized Prince Harry, 42, and his wife Meghan Markle, 45, over their relationship with the Royal Family.

She said: "You can't leave the Royal Family, then come back and pretend you are a Royal and then cash in on it. It's just a mess."

Plant believes Diana would have been devastated by the breakdown in the relationship between Harry and Prince William, 44.

She added: "She would roll over in her grave if she could see what was happening now. I think Diana, if she was still alive, would have bashed William and Harry's heads together long ago."

Plant was 12 when she met Diana during an April 1983 visit to Queensland.

She recalled: "She reached out and shook my hand. When she looks you in the eyes, there's something you can't put into words. I felt seen."

Plant's exhibition, Diana: Love Life Legacy – A Life of Giving, opens at the Ronald Reagan Presidential Library & Museum in California on November 7.