Featuring a steamy sex scene in Buckingham Palace and the grisly murder of three royal staff members, one of whom meets an untimely end by choking on a long service medal, The Hawk Is Dead is far from your typical royal narrative.

However, this intriguing story has caught the attention of Queen Camilla, a dedicated fan of crime thrillers, who might even have inspired some of the story’s cheekier elements.

What individual, I wonder, conceived the plot to assassinate the King’s longstanding aide, Sir Peregrine Greaves, a courtier renowned for being so smooth he seems to ‘glide on wheels’?

And where did the inspiration for the character of Baroness Westwood, known to her friends as Tiny, come from?

Surely not Camilla’s right-hand woman Jane von Westenholz – known as Lofty to her friends? Perish the thought!

Author Peter James clarifies in the introduction to his 21st Roy Grace novel that although the roles of the royal household staff are accurate, the characters themselves are purely his invention.

But for anyone with knowledge about the workings and personalities of the palace it makes for a fun game of Who’s Who.

In an exclusive for the publishing industry, a gripping first excerpt from this eagerly awaited mystery novel, set within the halls of the nation’s renowned royal abode, is being serialized for Daily Mail readers.

It might be unusual to see one of the UK’s top crime novelists (Peter James, who has 21 Sunday Times No1 bestsellers and over 23 million copies sold globally) transplant his beloved detective from the familiar grounds of Sussex to the intense undercurrents of a royal household. But this transition had been in the pipeline for years, as he explains during our conversation over tea in his writing sanctuary, 72 daunting steps up in a luminous Georgian tower at his beautiful Jersey residence.

Its panoramic views of the island are rivalled only by his eye-popping collection of crime memorabilia, from handcuffs to hats – plus a cheeky sign which reads: ‘Careful, or you’ll end up in my novel.’

With his slicked-back hair and penchant for top-to-toe black, James, 77, could easily pass for a villain in one of his own novels – but in reality couldn’t be more charming company. And while his book is not endorsed by the palace, it’s clear the author has had the opportunity for some extensive behind-the-scenes research there, as well as insight from members of the Royal Household – including the Queen herself.

His friendship with Camilla dates back to 2015 when he received an email from a friend telling him to rush out and buy a copy of the Daily Mail. On page three was a picture of the then Duchess of Cornwall in her office talking about her passion for literacy… with two of James’s crime novels on the shelf behind her.

He immediately wrote to the royal to say how he thrilled he was to see his work in the royal library and was shocked to receive a ‘charming and chatty’ handwritten note in return. ‘Mine is yet another fan letter,’ Camilla wrote (apparently she adores his ‘pretty terrifying’ storylines and the hero’s tragic personal life).

Since then the pair have become pen pals. In 2018, after accompanying Prince Charles to the opening ceremony of the Gold Coast Commonwealth Games, Camilla wrote that his latest page-turner had ‘kept me gripped on the endless journey to Australia’ and now she was wondering what on earth to read on the way back.

In 2021, shortly after Camilla started the Duchess of Cornwall’s Reading Room – set up during the pandemic to share her favourite book recommendations and now a hugely successful online book club and literacy charity – Camilla was invited to interview James for the book club’s website.

She visited him on the set of Grace in Shoreham, West Sussex – five series of James’ books have been televised for ITV, with a sixth in production – and met stars of the show, led by actor John Simm.

‘What I loved is that she knew more than me about my books and was completely unshockable. She liked the quite nasty and violent stuff. She’s definitely not a literary snob,’ he recalls.

After the official meet and greets, Camilla was scheduled to grab a bit of lunch in private before her next engagement. To James’s surprise, however, he was invited into the room by her private secretary, who proceeded to pull a Thermos flask of soup, a banana and a ham sandwich out of her handbag, which the King’s wife happily shared with him.

Some time later another cypher-headed royal missive from Clarence House dropped through his letterbox asking whether he might consider setting a future book in London? James did little more than mull over the idea until he was invited to speak at Camilla’s first ever Reading Room literary festival at Hampton Court Palace in 2023, when a member of the Royal Household mentioned that Her Majesty actually seemed ‘rather keen’ on the idea. Challenge accepted, thought James. ‘And where better in London than Buckingham Palace itself?’

The plot developed quickly: after learning that the palace was ‘slightly in chaos’ as a result of a ten-year, £369 million refurbishment, James decided it would present the perfect opportunity for someone to steal priceless items from the million-strong Royal Collection (including Granny’s Chips – the name given by the Royal Family to the famous Cullinan Diamonds, some of which are part of the Crown Jewels) and flog them on the dark web.

It wasn’t such a crazy idea, he was to later discover. In 2021 a palace catering assistant was jailed for stealing £100,000 worth of medals and photographs from the royal residence and selling them on eBay. ‘When I devised my plot, I sent it to a contact at the Royal Household who said they would “run it past HMQ when she is back from Kenya”. A week later I got an email to say “she laughed her head off and loved it” but they needed to get it approved by comms [Royal Communications]. To James’s amazement they signed it off in a couple of days.

‘Apparently a senior member of staff said: “Well at least Peter James had the courtesy to ask, which is more than some famous authors have.” So we were on.’

James has always been fascinated by the soon-to-be decommissioned Royal Train and decided to set his opening scenes with his unconventional detective hero being commandeered to oversee the Queen’s security on a ‘royal away day’ to visit hospices on the south coast.

Murder, however, ensues before Camilla even gets there as the train is derailed in a tunnel just outside of the city. As its claret-coloured carriages clatter off the tracks, a shot rings in the air.

Just who has derailed the royal train with Queen Camilla on board? And is it really an assassination attempt?

While Queen Camilla didn’t come up with the plot herself she did, however, speak to the writer several times about it. ‘I met her [on royal engagements] a few times while I was writing so I seized the opportunity to ask her little details like what she had for breakfast,’ he says.

‘Another occasion she asked how the book was coming along and I said: “Well, I’ve got you being quite heroic. The Royal Train is derailed in Clayton Tunnel on the way to Brighton and I’ve got you helping people off the train”.’ ‘Hmmm, I don’t know if I would be quite so brave really,’ Camilla amusingly remarked.

It’s fair to say that James has been given more access to the inner workings of Buckingham Palace than possibly any author in recent history as part of his research. On one fact-finding tour he switched on his fitness tracker and discovered he had walked three and a half miles by the end of it. ‘I once asked a member of staff how they found their way round the place as it’s such a rabbit warren. They said: “I asked the same question of Prince Philip about 15 years ago and he told me, “You navigate by the paintings, of course!” Trouble is they keep switching them, apparently!’

He’s quizzed everyone from senior palace figures to the King’s armourer and his novel is crammed with fascinating insights into royal life.

‘When they recently dug up the floorboards in the late Queen’s apartment to put down some new piping they found that half the planks had inexplicably been sawn through,’ James reveals.

Remarkably, it seems, Her Late Majesty could have accidentally plunged through the floorboards at any time in her 70-year reign.

‘I have spent hours at the palace, up on the roof, down the basement… everywhere [an old Georgian light shaft is the scene of a raunchy sexual encounter between two protagonists]. I really wanted to get the geography of my big chase scene round the palace right,’ he adds. ‘Everybody I have met in the household was really enthusiastic about the book. The only person less so was the head of the Royal Collection who was concerned the thefts ‘might make us look like we are a little inefficient’.

Reader, be assured that in reality Granny’s Chips are very much in safe hands. ‘In another scene I have Roy Grace being summoned by the King to his sitting room to discuss the case as he fears for his wife’s life. I had him standing up with his hands in his pockets but staff were quick to tell me, “No, he’d only have his hand in one”,’ James says. ‘And when I referred to them as Their Majesties I was told, “No, you are being too formal. Everyone calls them The Boss or HMK and HMQ”.’

The writer sent his first draft – under the codename 001 – to Queen Camilla earlier this year.

‘I sent the book with a note telling her it was the first and only copy in existence and would she be willing to have a read and let me know if there was anything she was unhappy with as she and the King featured as themselves so prominently throughout,’ he says.

‘I met her a week later at Clarence House [for a literacy event] and she came up to me beaming and said: “I absolutely loved it.”

‘Is there anything you are not happy with? Anything you would like me to change?’ And she said: “No, I don’t want a word changed. Not. A. Word”.’

Indeed I’m told HMQ even teasingly refers to one member of her staff by their literary pseudonym now and even King Charles is a fan. It’s something of a full circle for James, who describes himself as a ‘total royalist’.

His late mother was Cornelia James, a remarkable Jewish refugee from Austria who held a royal warrant as the maker of Queen Elizabeth’s gloves (she even made the pair for her going-away outfit following her marriage to Prince Philip in 1947).

‘My abiding memory is watching Bruce Forsyth on Sunday Night At The London Palladium on television at home and my mum sitting there with one of the Queen’s gloves and a needle and thread, repairing them. She wouldn’t let anyone else touch them.

‘The Queen and her dresser were very frugal and would always send them back to be repaired,’ he smiles. James’s sister, Genevieve, still runs the family business.

He has no doubt his mother would be thrilled by his own relationship with royalty – and he is full of praise for the new Queen’s determination to champion reading and literacy through her Reading Room, which he enthusiastically supports.

‘Some people have this attitude that if it’s not on the Booker Prize list then it’s not worth the paper it’s written on. In fact a lot of people will only say that crime is their guilty pleasure. But she makes no bones about how much she loves a good read,’ James says.

The Queen has, in return, made no secret of her admiration for the writer, publicly revealing that Roy Grace is her favourite fictional detective, an honour which James says brought him to tears.

When you read his thrillers it’s a shock to realise that for such a genuinely lovely man, James has a really rather morbid imagination (as part of his research, he once got an undertaker to lock him in a coffin to see what it felt like being buried alive.) ‘Yes,’ he giggles, his dark eyes twinkling. ‘People often say they are quite worried about meeting me but then they seem pleasantly surprised.’

With previous novels tackling issues as diverse as organ trafficking and county lines drug dealing, was he not slightly worried that the rarefied echelons of Buckingham Palace would fail to provide sufficiently gritty subject matter?

‘They have the same petty jealousies and coveting of offices you would find anywhere,’ he says, with a knowing look.

‘I only realised when I began talking to people how important medals are, for example, particularly the long service medals.

‘People would almost actually kill for one, you might say. ‘So, yes, I thought it would be a bit ironic to get a medal you really, really wanted stuffed down your throat.’

A particularly macabre ending – but one that seems to have tickled our Queen.

The Hawk is Dead: A Killer In The Palace will be published by Pan Macmillan on October 2l. Now read a gripping extract at dailymail.co.uk/royalthriller