Her hairdresser of 10 years tells never-been-shared anecdotes about the late Princess of Wales’ “amazing, wicked sense of humor” in a new book

Princess Diana on Jan. 27, 1988. Photo: PATRICK RIVIERE/AFP via Getty

As Princess Diana’s former hairstylist Richard Dalton put it, in his decade working with the late Princess of Wales, he probably spent more time alone with her than anybody.

His new book, It’s All About the Hair—My Decade with Diana — written with friend Renae Plant, the curator of The Princess Diana Museum — is filled with behind-the-scenes glimpses of a woman everyone thought they knew (after all, she was the most photographed woman in the world during her lifetime) but few actually did.

“After seeing her every day for over a decade, it was fun to relive the memories,” Dalton tells PEOPLE, adding one of his goals in writing the book was showing “how funny Diana was,” he says. “Just what a wonderful, genuine person that she was.”

In the book, Dalton recalled the royal’s “amazing, wicked sense of humor,” he wrote. “Her jokes were hysterical.” He said Diana was constantly telling jokes and playing pranks, adding that her sense of humor was “very naughty at times.”

Princess Diana in 1990. Photo by Jayne Fincher/Princess Diana Archive/Getty Images
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“She always had plastic vomit or plastic dog poop in her bag to place on people’s seats when we traveled on long flights,” according to Dalton, who worked with the princess from before her 1981 wedding to the future King Charles until 1991. He added, “She was hysterically funny and loved playing jokes on all of us.”

Plant, who turned Dalton’s memories into a 444-page book, tells PEOPLE, “I do find the humorous side of Diana to be very sweet,” she says. “She just wanted to be ‘normal’ and was just like the rest of us.”

‘It’s All About The Hair – My Decade with HRH Diana Princess of Wales’.The Princess and the Platypus Foundation

Diana was often able to laugh through life, Dalton writes, recalling a time when, after styling the Princess of Wales’ hair, he was followed by one of Queen Elizabeth’s corgis to a dressing room.

“I was patting it, as I love dogs, when Diana came up and the corgi started to lick her legs,” he wrote. “She said, ‘Whose dog is that?’ I said, ‘It’s your mother-in-law’s new corgi.’ She replied with a laugh, ‘Well, get it out of here, as it’s licking all the fake suntan off my legs.’ “

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Princess Diana watches Prince Charles playing polo at Guards Polo Club on Smiths Lawn in Windsor, Berkshire in July 1986.

David Levenson / Contributor / Getty Images

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As much fun as she was prone to have, Princess Diana was serious about her royal work, right down to her hairstyle.

“Diana was very conscious that she did not want her hair to overshadow the charity she was representing that day and supporting,” Dalton tells PEOPLE.

In his book, Dalton highlights Diana’s unwavering dedication to her work, noting, “She was genuinely interested in people and she always did her homework and remembered the smallest detail which made that connection.”

He adds of the princess, “She was more beautiful in real life than she was on camera.”

Beyond her appearance and sense of humor, Dalton says he hopes his new book shows the public “just what a wonderful, genuine person she was,” he says. “I hope it inspires them to be kind and treat others with compassion, just like she did while she was alive.”

It’s All About the Hair—My Decade with Diana is out now.