In his new blockbuster book, "The Way We Were," Paul Burrell says that Princess Diana had ambitions to become the first lady of the United States.
"She knew a billionaire in America, and she suggested to him that if they were together. … His yearning to run in politics could lead to the White House, that one day she could be the first lady and she'd visit Britain on a state visit," Diana's former butler and confidant said to "Good Morning America's" Kate Snow in an exclusive interview.
Burrell said that in the mid-1990s Diana had dreamed of following in the footsteps of stylish first ladies.
"She's been a huge fan of Jackie Onassis for years, and a huge admirer, too, of Nancy Reagan and Hillary Clinton. But Jackie Onassis had the edge. And she fantasized about redecorating the White House," Burrell said.
"It wasn't a fantasy. It could have been a reality. It really could. They would have been a golden couple."
While the mystery man in New York had political connections, he was not the love of Princess Diana's life.
Neither was Prince Charles or Dodi Al Fayed, Burrell said, who dismisses claims that Diana was engaged to Fayed when they died in a Paris car crash.
"She was not going to marry Dodi Al Fayed, because there was someone else in her life. She had a soul mate, and she'd fallen in love with someone else," he told Snow.
That man, Burrell said on "GMA," was a heart surgeon in London named Hasnat Khan.
It was love at first sight for the princess, he explained.
"They met by accident. The princess was visiting a friend at the Royal Brompton Hospital. The elevator was about to close. Someone put their foot in the door. The doors open, and the princess saw a man in his scrubs."
"She looked at him and instantly knew that he was the one. She said to me later, 'Paul, I just knew. He was drop-dead gorgeous.'"
Burrell says the princess fell deeply in love with Khan, leaving him messages at the hospital using a secret code name for herself -- Dr. Allegra.
Their two-year relationship was rocky, according to Burrell. One night Diana couldn't find Khan, so she sent her butler out looking for him.
"I found him in the local pub, slumped in a corner, with a beer, with a cigarette," Burrell said. "So I sat down with him and had a heart to heart. Two men in a pub, with a pint."
The next morning, Burrell received a handwritten thank you from the princess.
Burrell read from the letter on "Good Morning America":
"September the 16th, 1996. Dear Paul, Not many people would venture out late at night to sort out a heart, basically on a stranger's door. But then, not many people have the kindness and qualities you possess."
Burrell told Snow, "I did everything I could to make sure that she was happy."
Diana's relationship with Khan ended, Burrell said, because the doctor didn't want to go public.
"It's hard. Once the princess said to me, you know, 'Who's going to marry me, Paul, with all my baggage?'"
When the princess died, Burrell said he had a secret rendezvous with Khan.
Just before he left to meet the doctor, Burrell said he saw a hair band that belonged to the princess sitting on a table.