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In November 1995, Stewart Pearce was invited by his pal Mara Berni to have lunch with a mystery guest. When he arrived at London’s San Lorenzo restaurant, he found Princess Diana waiting for him.

"Diana grabbed hold of my arm and said, ‘You will work with me, won’t you?’" the voice coach recalled to Fox News. "I was met by these extraordinary incandescent blue eyes. She was just stunning. At that very moment, I said, ‘Yes, absolutely. But let’s make sure our relationship is completely confidential.’ She had worked with a number of people over the years and they betrayed her to the tabloids. But I told her, ‘This relationship will be completely confidential so I can support you in this journey of empowerment.’ And that’s what I did for the last two years of her life."

Pearce, who worked with Margaret Thatcher and the Royal Shakespeare Company before he befriended the Princess of Wales, has recently published a book about their work together titled "Diana The Voice of Change." It explores her life principles and how she became "a force of liberation" as a royal before her untimely death.

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Voice coach Stewart Pearce said he didn't expect Princess Diana to be waiting for him at a lunch meeting that forever changed his life.

Voice coach Stewart Pearce said he didn't expect Princess Diana to be waiting for him at a lunch meeting that forever changed his life. (Photo by Anwar Hussein/Getty Images)

"My initial impression was that she was one of the most beautiful, one of the most adorable, one of the most sensitive people that I’ve ever had the honor of meeting," said Pearce. "She wanted to achieve vocal assurance. She wanted to achieve vocal presence."

"She wanted to achieve an ability to formally speak and feel grounded and centered in public engagements," he continued. "Because up to that point, she had not felt easy. She was an immensely sensitive empath and walking into the flashing lights of 500 cameras was really disturbing to her. She wanted to feel more confident, more assured, more grounded when she spoke to people. And towards the end of her life, she began to achieve that."

For nearly two years, Pearce worked with Diana in private one-on-one sessions where she would improve on her confidence as a public speaker. And it didn’t take long for the two to become friends.

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Stewart Pearce said he and Princess Diana became fast friends.

Stewart Pearce said he and Princess Diana became fast friends. (Photo by Neil Munns - PA Images/PA Images via Getty Images)

"What surprised me the most about her? Her absolute immediacy," said Pearce. "Her absolute authenticity. She had a way of making people feel, even in the most formal situations, very informal and very easy."

And Diana had no problem letting her hair down.

"Whenever she arrived for a session, she would always say to me, ‘Do you have any washing up?’" Pearce chuckled. "I do mean washing China or crockery. It was her way of becoming grounded and ordinary. Before she married Prince Charles, she lived in an apartment with three girlfriends. She loved house cleaning. She absolutely loved it. I would laugh whenever a guest came by and I provided them tea. Because I remember Diana coming in and saying, ‘Can I do any washing?’ She would say to me, ‘Can I iron any of your shirts?’ She loved ironing. I would tell her, ‘Darling really, no, I can’t have you ironing my shirts, but I will leave the China for you to wash up.’"

"We would laugh a lot," Pearce shared. "She was just so much fun and could be really naughty with her humor. It was never at anybody’s expense, but we would laugh so much that sometimes we would even forget what we were laughing about. And you couldn’t help but laugh because that laugh of hers was just so infectious."

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Stewart Pearce said Princess Diana wanted to be more confident in her voice as she embarked on the next chapter of her life.

Stewart Pearce said Princess Diana wanted to be more confident in her voice as she embarked on the next chapter of her life. ( AP Photo/Jim Bourdier)

But when it came time to do work, Diana was very determined to be heard.

"My work with her was just so easy," said Pearce. "She felt trapped in what she called ‘The Prison of Windsor.’ But when she began to speak, she felt liberated. If we have a problem and stash it away inside of us and it disturbs us, as soon as we begin to speak about it, we begin to feel better. And Diana felt liberated when she spoke out. For a very long time, she was being ignored by Charles, a sensitive man who didn’t know how to deal with it all. And in turn, Diana went through a lot of anguish.

"She didn’t feel heard by the royal family, which are extraordinary people, but at times can find emotional vulnerability unusual to behold. They tend to be very private about the way they experience or express emotion. She was there as an agent of change. She was there to liberate the consciousness of what was going on within the family. And I’m sure she did a tremendous job to allow them to become slightly less removed and slightly less tight-lipped."

Diana was just 20 years old when she married Charles, heir to the throne, in 1981. They welcomed a son named Prince William in 1982, followed by Prince Harry in 1984.

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In this July 29, 1981 file photo, Britain's Prince Charles kisses his bride, the former Diana Spencer, on the balcony of Buckingham Palace in London, after their wedding.

In this July 29, 1981 file photo, Britain's Prince Charles kisses his bride, the former Diana Spencer, on the balcony of Buckingham Palace in London, after their wedding. (AP)

But the marriage was rocky and heavily scrutinized by the tabloids. The couple separated in 1992 and they later divorced in 1996.

"Diana was placed into a situation where she was not understood by the institution," Pearce explained. "… I had an insight into it. My father worked for the Duke of Edinburgh for 33 years. But Diana created a revolution within that. She continued to be a compassionate, empathetic person who was reaching out for inclusivity."

Pearce said he and Diana spoke shortly before she jetted off to the South of France with her new boyfriend Dodi Fayed. Pearce described Diana as feeling excited about her trip and eager for what the future held for her. 

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Princess Diana enjoys the splash of a wave during a morning swim on the Caribbean Island of Nevis January 3, 1993. REUTERS/Mark Cardwell - GM1DUGTOYZAA

Stewart Pearce described Princess Diana as "a real fish" who loved swimming. (Reuters)

"She was very excited," said Pearce. "She loved swimming. She swam once a day. She was a real fish. She loved the idea of being on the Mediterranean and being on a yacht. Dodi was a very kind, gentle, loving man. Was she in love with him? I don’t know. But she was certainly having a good time. Here was a beautiful young woman enjoying herself while receiving attention from a handsome lover. Why not?"

But according to Pearce, her last words to him were prophetic.

"There was a certain wistfulness in her face," he reflected. "I remembered we said goodbye and hugged. She then said, ‘Wouldn’t it be wonderful if all the things we’ve done together could be written in a book? But let’s make sure it’s done when the children are married.’ It always haunted me. Her death was a terrible shock. It was extraordinary."

Diana passed away in 1997 from injuries she sustained in a Paris car crash. She was 36.

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A permanent memorial to Diana, Princess of Wales and Dodi Fayed is pictured in the Harrods store in London, 31 August 2006, on the ninth anniversary of their death. Diana, 36, and her boyfriend Dodi Fayed, 42, were killed in a car crash in Paris in the early hours of August 31, 1997. 

A permanent memorial to Diana, Princess of Wales and Dodi Fayed is pictured in the Harrods store in London, 31 August 2006, on the ninth anniversary of their death. Diana, 36, and her boyfriend Dodi Fayed, 42, were killed in a car crash in Paris in the early hours of August 31, 1997.  (JOHN D MCHUGH/AFP via Getty Images)

On Thursday, the day that Diana would have turned 60, her sons unveiled a statue honoring her life and legacy.

Pearce hopes his book will empower readers, especially women, to share their voices and speak out to make positive changes in their lives.

"Diana shook the world into a new reality," he said. "There was a radiance to her. The book begins with love and it ends with love."

The Associated Press contributed to this report.