Princess Diana’s hairdresser is sharing details about a “total scandal” that had then–Prince Charles — now King Charles —“ranting and raving” while drawing a starkly different response from the late princess.

Richard Dalton, who served as Diana’s official hairdresser from 1981 until 1990, tells PEOPLE that the royal couple found themselves in the middle of an uproar during their April 1983 tour of New Zealand.

“There was a big hoo-ha going on,” Dalton says, referring to anti-monarchist Māori rights protests at the time.

According to Dalton, one Māori protester “lifted his skirt and showed his ass to the princess” during a haka, a traditional Māori greeting ceremony intended to welcome King Charles, then Prince Charles, and Diana to New Zealand.

“Total scandal,” he continues.

Dalton overheard Charles’ reaction to the incident when he went to style Diana’s hair and set her tiara that evening.

“I was waiting that evening to go and do her tiara, and I could hear the prince was ranting and raving next door,” he says.

Diana, on the other hand, was laughing over the episode, per Dalton.

“He doesn’t sound too happy. I heard what happened,” Dalton recalls telling Diana of Charles. “She said, ‘I dunno what he’s going on about. It’s the best thing that ever happened to me since I arrived.’”

Dalton also opened up about the “scandal” in his memoir, It’s All About the Hair—My Decade with Diana, written with friend and founder of  The Princess Diana Museum, Renae Plant.

“She was so funny,” Plant tells PEOPLE of the princess. “I can’t even begin to tell you. There are all these cards and things that she would give people that are just so dirty and wickedly, crazy funny. She had so much fun.”

At the time, protests against Diana and Charles’ visit sparked headlines such as “Maori moon shines on royals.”

“A Maori protester wearing a grass skirt broke through police lines Wednesday and flashed his bare bottom in the direction of Prince Charles and Princess Diana,” read an April 20, 1983, UPI article.

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Documents kept in Britain’s National Archive and released by the Foreign, Commonwealth and Development Office in 2021 shed further light on the incident.

In a letter to the Foreign and Commonwealth Office marked “confidential,” then New Zealand High Commissioner Sir Richard Stratton wrote, “A well-known Maori agitator presented his bare – and hideous! – bottom (allegedly the worst Maori insult, but I have my doubts!) to Their Royal Highnesses as they drove into Wellington from the airport.”

Diana and Charles’ New Zealand tour was the only time the princess would visit the country, one of the 56 countries in the British Commonwealth.

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