Long before it occurred to Prince Harry, The Duke of Sussex to tell – and sell – his truth to the world, there was Paul Burrell.

He was far more than just Diana, Princess of Wales’ butler but her confidant, her Cerberus, and in her own words, her “rock” and for more than two decades now though he has been milking his time with the royal family like a veteran dairy worker.

Now, he’s back at it, having written his third tell-all and has revealed an extraordinary conversation he had with the late Queen in the aftermath of Diana’s death who warned him that there were “forces at work” which even she did not know about.

Burrell’s account comes as there is renewed noise and clamour about the circumstances surrounding the princess’ 1997 death in Paris with reports that Harry could be considering making a documentary about his mother.

The thing is here you don’t have to particularly like Burrell, a man who might have the rare honour of having appeared on three nations’ I’m A Celebrity (UK, South Africa and Australia) and have made himself into the crassest of reality tele stalwarts (‘an envelope being opened you say?’) but that does not change the fact that he was in the room – nearly every room – after Diana’s death.

He arrived in Paris hours after her death, dressing her body for her final flight back to Britain. Which is to say, there are few if any other people who had such a front-row seat to this particular chapter of horribly sad history.

The story he tells in his new book, The Royal Insider: My Life with the Queen, the King and Princess Diana, goes like this.

It was late 1997, four months after the princess’ death, and he had been tasked with “cataloguing and packing away every item in the Princess’s world” however, he was worried, fearing that her legacy was “at risk of being destroyed” as her mother Frances Shand-Kydd shredded her the princess’ papers.

So Burrell contacted Paul Whybrew, one of Queen Elizabeth’s most trusted aides (who held the brilliant title Page of the Backstairs) to arrange a meeting.

(Whybrew, known as Tall Paul, worked for Her late Majesty for four decades and so close were they she chose him to appear in her 2012 James Bond sketch for the London Olympic Games.)

On December 19, 1997 Burrell arrived at Buckingham Palace for tea with the late Queen.

“I have never recounted much of my conversation with the Queen that day, but I now feel the time is right,” he says in The Royal Insider.

“It sheds a light on her character. I was concerned that the Queen had no idea what was happening inside Kensington Palace.”

He writes that, after being ushered into what could sounds like the late Queen’s private apartments, “a mix of grey and salmon pink … Her pile of Telegraph crosswords, her dog treats, her magazines”, the pair settled in for that most British of meals.

“We talked of the dreadful day Diana died, and what I witnessed in Paris before the arrival of the Prince of Wales and Diana’s sisters,” he writes. “It must have been awful for you,’ she said

“She offered me a stark warning: ‘Do be careful. There are forces at work in my country of which even I have no knowledge.’”

Sadly, that was that, tea over, jammy dodgers eaten and we are left with nothing but questions about what “forces” the late Queen might have been alluding to.

However, this was not the only occasion on which the ever rational late Queen, a woman who was a byword for stolid British sensibleness and hardly given to wild conjecture and flights of conspiratorial fancy, expressed views suggesting Diana’s death was more than just a tragic accident.

Hours after the crash in Paris, when the world thought that the princess had suffered a broken arm and other injuries but had survived, a witness heard the Queen comment, “Someone must have greased the brakes”, according to veteran royal biographer and Majesty editor-in-chief Ingrid Seward.

So too Andrew Morton, the man Diana turned to secretly tell her story in the early 90s, who has also reported that Queen Elizabeth made those “brakes” comets.

He wrote that “Her reaction shocked and puzzled her staff, who’d rarely heard her use such colloquial language. Was the Queen implying that Diana had been a target?”

In the years before her death, no lesser source than Diana herself was telling those in her inner circle she feared for life.

In 1993 after her separation from then Prince Charles she wrote to Burrell: “This particular phase in my life is the most dangerous – my husband is planning ‘an accident’ in my car, brake failure and serious head injury”.

(Though Diana thought this was “to make the path clear for him to marry” Prince William and Harry’s trusted nanny Tiggy Legge-Bourke and that “Camilla is nothing but a decoy” which doesn’t exactly redound to the princess’ acuity.)

Two years later, in October 1995, Diana summoned her legal adviser Lord Mishcon, her divorce lawyer Maggie Rae and solicitor Sandra Davis, to Kensington Palace where she told the trio she thought her life was in danger. During the meeting the Princess of Wales said that “reliable sources” had told her that “efforts would be made, if not to get rid of her, be it by some accident in her car, such as pre-prepared brake failure or whatever … at least to see that she was so injured or damaged as to be declared ‘unbalanced’.”

Lord Mishcon wrote a memo about their conversation after the meeting and that he had told her “if she really believed her life was being threatened, security measures, including those on her car, must be increased”.

However he also noted, “I frankly, however, couldn’t believe that what I was hearing was credible” and that her private secretary Patrick Jephson “half believed” her claim.

Rae later told the official UK inquest into Diana’s death “It was very clear in my own mind that she thought she was going to be killed.”

Likewise, Davis told the inquest that the princess had been “deadly serious” about her concerns, and that they had informed the police.

After Diana’s death, Davis later said, she had felt sick and “My mind jumped to what she had said during our meeting”

(18 days after Diana’s death in 1997, Lord Mishcon took the memo to Scotland Yard where it was kept in a safe for years before finally coming out during the British investigation.)

In 1995 also the princess called her healer Simone Simmons on the phone to tell her that the brakes on her car had failed and she feared it was intentional.

The HRH later reiterated the claim, writing a note to Simmons saying, “Dear Simone, as you know, the brakes of my car have been tampered with. If something does happen to me it will be MI5 or MI6 who will have done it. Lots of love, Diana.”

Simmons later told the British inquest that Diana believed she was going to be “bumped off” after she began her groundbreaking anti-landmine campaign.

Before her death Diana was compiling a dossier titled Profiting Out of Misery, Simmons revealed, in which she would “name names” of those in the UK profiting from landmines.

The princess gave Simmons the six-inch thick dossier which she kept under her mattress however later burned it, explaining “I was more than nervous. If I had the material, I might have been bumped off as well.”

Once Diana sent her a note which said: “If something happens, MI5 or MI6 will have done it.”

“Top of her list of culprits was the Secret Intelligence Service which she believed was behind the sale of British landmines that were causing so much misery to so many people,” Simmons has said.

It’s impossible to know how much credence to put in any of this.

The landmine business was worth hundreds of millions of dollars, according to Human Rights Watch, in 1997 but also, Prince William himself has commented on his mother’s “fear, paranoia and isolation” during “those final years with her.”

One thing I always find incredibly sad is that at the end of Diana’s life, she was the most famous woman in the world, adored if not revered, and yet in private she was isolated and often alone.

Her divorce lawyer Rae told the British inquest, “One weekend she told me about she had been alone in this rather lonely set of apartments, she had heated her own food in the microwave, I got the impression that she was a bit lonely.”

In July 1997, six weeks before that fateful night in Paris, Diana lunched in New York with former Vanity Fair editor Tina Brown and Vogue impresario Anna Wintour.

The princess seemed “terribly lonely”, Brown later said and wrote in her excellent The Diana Chronicles that at lunch “she was already worrying … about where she might go in August” for her summer holidays. Staying at Kensington Palace on her own “will be so difficult with the boys” she told Brown and Wintour.

Then, Mohammed Al Fayed invited her to stay. I don’t need to tell you what happened next.