Their chemistry and connection was said to be instant and now and an unauthorised new biography, called The Duchess: The Untold Story by royal reporter Penny Junor, shows just how much Prince Charles pined for Camilla Parker Bowles when they first met.
Speaking to the couple's inner circle, Junor has unearthed a series of explosive stories, which have been published on The Daily Mail.
According to the book, Prince Charles was devastated when Camilla decided to wed army officer Andrew Parker Bowles in 1973.
The pair had met two years earlier after being introduced by Lucia Santa Cruz and hit it off, but Charles' beloved great uncle and trusted confidant, Lord Mountbatten, advised him against pursuing anything more serious as she wasn't "sufficiently aristocratic" or a virgin - two very important things back in those days when selecting a royal bride.
Despite this, the Prince of Wales still harboured a very deep love for Camilla.
When news of her engagement broke, Camilla penned a letter to Charles while he was working for the Royal Navy in the Caribbean.
Her news did not go down well with the royal.
“She wrote to Charles herself to tell him. Her letter broke the prince’s heart. In great distress, he fired off anguished letters of his own to his nearest and dearest."
“It seemed to him particularly cruel, he wrote in one letter, that after ‘such a blissful, peaceful and mutually happy relationship’, fate had decreed that it should last a mere six months," an excerpt of the book reveals.
"I suppose the feeling of emptiness will pass eventually," a broken-hearted Charles apparently told friends.
RELATED VIDEO: Camilla’s son talks about Prince Charles. Post continues after the video...
Like something out of a rom-com, Charles made a "last-ditch" effort and wrote Camilla a letter begging her not to marry Andrew just a week before they were due to wed in July, 1973.
It didn't work but the pair remained close friends before things progressed into an affair around 1978, shortly after Camilla welcomed her daughter Laura.
“Andrew was in no position to complain; and when he discovered what was going on, he wisely didn’t make a fuss,” the biography explains.
“Some would say that a part of him actually quite enjoyed the fact that his wife was sleeping with the future King; he might have felt differently had Charles been a traveling salesman.”
As for why Charles was so enamoured with Camilla, according to Junor "he loved the fact that she smiled with her eyes as well as her mouth, and laughed at the same silly things as he did. He also liked that she was so natural and easy and friendly, not in any way overawed by him, not fawning or sycophantic."
"In short, he was very taken with her, and after that first meeting he began ringing her up.”
Of course, Diana was well aware of their dalliances and as Penny writes in her book, in the lead up to Princess Diana and Prince Charles' wedding in 1981 her jealously became came to the fore.
"There were terrifying rages, temper tantrums, hysterical tears for no apparent reason, and her moods changed in a flash," Penny writes.
"She became jealous — obsessing about Camilla and turning against people she'd appeared to like, convinced they were out to get her, undermine her or spy on her."
It wouldn't be until after Princess Diana's death and the breakdown of Camilla's marriage to Andrew that the pair would finally give their romance a proper shot. In 2005, Charles and Camilla wed in a civil ceremony.
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