Novelist Jeffrey Archer Learned the Secret to Stealing the Crown Jewels...from an Unlikely Source with Royals Ties

Jeffrey Archer's new book, 'Traitors Gate,' details an audacious plot to steal the Crown Jewels from the Tower of London

The inspiration for storyteller Jeffrey Archer’s new novel about a plot to steal the Crown Jewels came from an unlikely place: the royal household!

A little nudge over dinner one evening from someone who had worked at the royal household was enough to get the famed author plotting: Could the unthinkable be done?

Archer, 83, whose books have sold around 275 million copies across the world, came up with the idea for his novel Traitors Gate as he and his wife, Dame Mary Archer, were taking their first vacation post-COVID, the guests of Tors Hagen, the owner of the Viking Cruise line. Archer won’t reveal the name of the person seated next to him at dinner on the ship.

“I've read your books, Jeffrey, and I've got a story for you!” Archer recalls his neighbor learning over and conspiratorially telling him that night.

“And then he added to the sin by saying, ‘I can tell you how to steal the crown jewels.’ In three minutes, the person told me how you could possibly do it. Of course, I didn't sleep that night. And by the time I'd got back to London, I'd written a 50-page outline — some holiday!”

Now Archer has written it, even though it is based on what might have been the case two decades ago, his contact (who has retired) is “very nervous.” It hinges on the circumstances of the Imperial State Crown being out of the Tower of London for the State Opening of Parliament.

“My immediate reaction was to assume that you wouldn't get anywhere. But that's not true,” he tells PEOPLE of the plot.

Related: How to See King Charles and Queen Camilla's Coronation Jewels After the Crowning Ceremony

When Archer was back in London, he used his contacts in the world of politics (he worked closely with Prime Minister Margaret Thatcher in the early 1980s and is a life peer in the House of Lords), the palaces and the police to piece together what he hopes is a believable storyline.

Archer got help with his research with his route from the palace to the Tower (the escort apparently takes one of six different ones) from a cab driver who “showed me all along the route how to slow the whole process down between Buckingham Palace and the Tower of London. He gave me another seven minutes,” which was crucial to the plot.

And he consulted a retired warden for some of the inside knowledge of the Tower of London. As a life peer, he could research the House of Lords where Queen Elizabeth would give her speeches to Parliament himself. “I walked the route where the Queen went, I went to the robing room, went in into the chamber, did everything except sit on the throne," he says.

At the Tower, he was scolded for taking photos inside the jewels exhibit. Outside, Archer was rumbled by some eagle-eyed wardens. “They saw me making notes outside Traitor’s Gate, and two of them came up and said, ‘Hello. One of your books?’ When I said yes, they said, ‘We’re in trouble, aren't we?' ” he smiles.

A key to making the plot believable both to him and his readers was that the Imperial State Crown could be copied — and he enlisted experienced jeweler Alan Gard from London's Hatton Garden jewelry district to help him. Over 18 months and 500 hours of work, Gard created a likeness of the magnificent crown, using glass for the almost priceless stones in the original. “I was asked to make it good enough so that when you’re five feet away from it, it would be good enough to fool people – or members of the House of Lords,” Gard, 87, tells PEOPLE.

For those who fear that the author, whose bestseller Kane and Abel is on its 132nd reprint, has now opened Pandora’s Box to tempt the unscrupulous, Archer says the information he was told is the circumstances of at least 20 years ago as his tipster doesn’t work close to the royals any more. Moreover, he doesn’t fear opprobrium from the royals, who only in May paraded the jewels at the coronation of  King Charles and Queen Camilla.

That’s because Queen Camilla, 76, reads his book and currently has a copy of Traitors Gate. “She got it three days ago in Balmoral,” he recently revealed in his penthouse apartment high above the River Thames in London. “I told the Queen, and you can’t get much higher than that."

Archer was also friendly with the late Princess Diana — and a photograph of her in a silver frame, which she had engraved with a facsimile of her familiar signature, takes pride of place on a side table in his London home. He had got to know her through auctions that helped some of her charities. (He plans to auction off the fake crown soon.)

He says of Princess Diana, “She was very beautiful, very seductive and very cunning. But historically, we all think the same thing: It would've been better if [Charles] had married Camilla in the first place. That's what we all think.”

“It's commonly known that she rang me four days, three days before she died, from Paris. And the press would keep coming back and saying, 'What did she talk about?' That's something I just don't think I can ever say. She rang privately."

"Of course. I didn't give it a second thought. Because I thought she was gonna live another 30 years. But it suddenly became very relevant to what happened.” He refuses to elaborate on the call.

Another icon of our times, the late Queen Elizabeth, appears in a fleeting but crucial moment in Traitors Gate. Though he met her a few times, he doesn't claim to have known her. "She has one or two sentences, which I did give a lot of thought to. It’s got to sound like the Queen."

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Archer was at the ballet that afternoon when news broke that the Queen was ill and then died. He'd written Traitors Gate by then and handed it into his publisher — and certainly wasn't expecting the Crown Jewels to be so fresh in minds due to the ensuing coronation of King Charles. Archer adds, “My immediate reaction was not to believe it, because I thought that she'd live to 100.”

Traitors Gate, published by HarperCollins, will be available on both sides of the Atlantic on Sept. 26.

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