Jane was 23 and a bubbly blonde, while he was 30 and the most eligible bachelor in the world. Diana was not on the scene, and although Charles was even then attached to Camilla, he also wanted to have fun.
Charles invited Jane to Windsor Castle and after an intimate supper in what was called the Nanny's Room, he leaned over and kissed her. It lasted so long they were both out of breath. Then, taking her hand, he led Jane to his bedroom where they spent hours in each other's arms.
Jane has told friends that Charles was an experienced lover, caring and sweet.
It was the start of a wild affair with the Prince spending many nights at Jane's cottage at Windsor.
At one polo club dinner, Charles shocked everyone by snatching Jane's hand and leading her from the ballroom and into the garden where they vanished in the bushes.
"We kissed and we talked and we had lots of fun," Jane told a friend. "Everyone knew where we were but we just didn't care. It was bliss." But Jane sometimes found Charles rather formal - even in his lovemaking.
The friend added: "She used to tease him about it and called him Teutonic. They found that kissing and stroking each other helped them relax."She was an extrovert in bed while the prince was restrained. She taught him to be more adventurous."
"But when Jane went a bit over the top he'd tell her she was being sent to the Tower.
"Charles was also unsure about his physique. He thought he walked strangely and felt he had stubby fingers. Jane reassured him."
But the affair fizzled out after it was revealed in a newspaper report with the headline "My Friend Charles, By Jane, 23." Major Ferguson was at first furious, rushing over to her at a polo match and screaming..."Jane, you stupid f****** bitch."