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You might think you know everything about Kate Middleton and Prince William’s 2011 royal wedding, but aside from the public pomp and pageantry, it turns out there was a private late-night celebration.

Princess Kate’s brother, James Middleton, shared some inside details from the party in his new memoir, Meet Ella: The Dog Who Saved My Life—and its theme was very different from the historic ceremony at Westminster Abbey.

In the book, James wrote of the “bustling” but “calm” atmosphere at the Goring Hotel, where he stayed with his family (including the royal bride) during the wedding festivities on April 29, 2011.

While taking his dog, Ella, out to the property’s “garden to potter around,” he came across a rather surprising find.

“There, a replica of Basil’s Bar in Mustique—a small private island in the Grenadines and a holiday spot the family had visited many times—has been set up,” the royal sibling penned. Describing the watering hole as the “social heart of the island,” James noted that celebrities like Jon Bon Jovi and Mick Jagger had put on performances at the “unassuming little venue.”

“Now a perfect facsimile of it has been built in the grounds of the Goring Hotel so wedding guests can imagine themselves on the edge of the Caribbean while actually in the middle of a London garden,” the book reads.

The Middletons are such regulars at Basil’s Bar that its owner, named (surprise!) Basil, was even “one of the wedding guests,” James pointed out.

Hilariously, James’s dog “managed to visit the bar before any of the other guests,” per Middleton. Lucky pup.

While Kate’s brother didn’t reveal any other details about the Caribbean-themed bash, one thing we do know is that the now-Princess of Wales changed out of her white lace Sarah Burton for Alexander McQueen wedding dress into a satin ballgown for the private evening reception. Whether she had a secret third dress for the island-style party remains to be seen.

However, Buckingham Palace was transformed for the lavish reception, with Ellie Goulding playing a set and a guest telling the Telegraph, “there was a huge bar in the middle of the room, lots of sofas for everyone to lounge on when they weren’t on the dance floor, and a stage for the band.”

As for their hotel bash, perhaps one day the Prince and Princess of Wales will treat us to a picture of Basil’s Bar 2.0.