Prince Harry has revealed he lost his virginity aged 17 in a field behind a pub with an older, horse-loving woman.
The identity of the woman, though, remains an enigma although the royal described the encounter as "humiliating".
Harry shares intimate details of the experience in his new book Spare, in which he writes: "A humiliating episode with an older woman who liked macho horses and who treated me like a young stallion.
"I mounted her quickly, after which she spanked my ass and sent me away. One of my many mistakes was letting it happen in a field, just behind a very busy pub. No doubt someone had seen us."
But Harry does not reveal the identity of the woman in his memoir.
At the time, the young prince was linked to the 23-year-old former model and keen horsewoman Suzannah Harvey.
Harry was said to have hit on Miss Harvey, now the chief executive of Cotswold Airport, at the Beaufort Hunt Christmas Ball held in a marquee in the grounds of Badminton House in Gloucestershire.
Speaking to the Daily Mail last night, mum-of-two Miss Harvey said Prince Harry's memoir was not something she wished to discuss.
She declined to talk to a reporter who called at her Cotswold home, adding she was away but her boyfriend was there.
Speaking after the Beaufort Hunt Christmas Ball, Miss Harvey had told Daily Mail : "I couldn't believe it when he made a beeline for me.
"It was very nice, but as we were kissing I started to get worried that his bodyguards would be looking for him. I didn't want to get him into trouble.
"It was so heated, steam was rising from us into the freezing cold air."
It's said Harry's fumble in the field happened behind a pub in Wiltshire when he was still a pupil at Eton.
Prince Harry has been linked to other older women over the years, including actress Liz Hurley.
Ms Hurley, who at 57 is nearly 20 years older than the royal, quashed rumours in an interview with The Times this week.
The actress and model, born in Basingstoke, Hampshire, said: "Not me. Not guilty. Not me. Absolutely not."
Harry was also said to have pursued interior designer Catherine Ommanney – 13 years his senior – when he was 21 in 2006.