He cut the princes’ hair until 1991, the year Prince William turned 9 and Prince Harry turned 7, and spent much time with Diana during the years he worked for her.

“It was every day, sometimes twice a day for tiaras,” said Dalton, who is set to publish a new book titled It’s All About the Hair — My Decade with Diana with The Princess Diana Museum founder Renae Plant.

“I would see her every morning, and obviously she had an event every day [and would] come back at 5 o’clock to do tiaras,” he said of his usual routine with the Princess of Wales. “I don’t think we were ever serious, it was always fun.”

“She would call me at Windsor Castle and say, ‘Can I come have my hair done at your apartment?’ She used to love coming to my house because it was normal,” Dalton recalled at the Styling Diana panel alongside Diana’s wedding dress designer Elizabeth Emanuel, in a conversation moderated by PEOPLE’s Senior Royals Editor Erin Hill.

Princess Diana also had an affection for a soap opera popular in the 1980s and didn’t like to miss an episode.

“She would say, ‘Richard, you can’t go out tonight because Dynasty is on!’ I had to watch it in great detail [for her],” he said. “That was my Elnett days, would travel with gallons of it. It was on the news that [King] Charles had banned aerosols at Kensington Palace and I thought, ‘Oh dear,’ ” he joked.

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From events in London to royal tours around the world, Dalton closely collaborated with Diana on choosing accessories as well — and said, for a time, she was inspired by Dynasty.

“Fashion, jewelry, she used to pretend she was in Dynasty. She [had] gone to see Back to the Future, [so we] tied the pearls in a knot,” the stylist said about the daring way they highlighted the open back of the royal’s red velvet dress at the movie premiere in 1985.

More seriously, he later described working with Princess Diana as the experience of a lifetime.

“[She was] extremely, extremely special. Her beauty was from within,” Dalton said. “She was more beautiful in real life than any picture.”