The Duke of Sussex claimed the "humiliating experience" happened in a field outside a "very busy pub" in the countryside when he was 17 years old.
Initially there was speculation about who this mystery older woman was, but since, Sasha Walpole has come forward to claim that she is the one who was involved in the tryst.
Walpole, 40, spoke to the Daily Mail and The Sun, claiming that the incident took place after they had been drinking at the Vine Tree Pub, Wiltshire, where they were celebrating her birthday.
She said she decided to reveal her identity now because of how much speculation there has been about the encounter, explaining that she felt it was a matter of time before her name went public.
In a new interview that aired on Piers Morgan Uncensored, the digger driver described her “disbelief” that Prince Harry had gone “into so much detail” about losing his virginity to her in his book.
Harry said he lost his virginity with an older woman who treated him like a "young stallion" in his memoir: "I mounted her quickly," he wrote, "after which she spanked my ass and sent me away."
Walpole didn't object to the "horsey context", she previously told the Daily Mail, but spoke about some of her regrets about the moonlight tryst in the interview with Piers Morgan, which aired on TalkTV on Thursday night.
Watch: Sasha Walpole reveals how heartache and alcohol fulled her romp with Prince Harry
"The thing wrong about it was we were two friends and it should never have happened," she explained.
"We crossed the line, it was never intentional there was nothing before, nothing after,” she continued. “I mean inglorious? It's not really that glorious sleeping with someone in a field behind a pub when you are drunk.
"There is nothing glorious about being drunk and then copping off with one of your mates, in a field."
Walpole confessed that part of the reason she chose to come forward was that people she knew were being "questioned" about the encounter, and that she had hoped she would be able to return to "normality" after the media “whirlwind”.
"Hopefully it's a means to an end and I can get back [home], and [go] back to normality, go back to work, drive my digger - hide back under my rock,” she added."
Since Spare's release, readers have been treated to never-before-seen insight into his relationship history.
Here, in addition to Sasha Walpole, Yahoo UK looks back at all the people Harry has been romantically linked with over the years.
Walpole has claimed to the be "older woman" who Harry lost his virginity in a field outside a pub where they had been celebrating her 19th birthday.
She alleged to the Daily Mail that she and Harry had been friends for a couple of years before their sexual encounter, which she called a "fiery, wham bam [experience] between two friends".
"It was instant, fiery, wham bam, between two friends. It was sparky because we shouldn't have been doing it. He wasn't 'Prince Harry' to me, this was Harry, my friend, and the situation had got a little bit out of control. It felt naughty, I suppose, in the sense that it shouldn't be happening.
"We didn't set out to do it – it wasn't premeditated and I didn't know he was a virgin. There were no virgin vibes – he seemed to know what he was doing. It was quick, wild, exciting. We were both drunk. It wouldn't have happened if we weren't."
Davy was Harry's longest previous romantic relationship running on and off from 2004 until 2010. It was widely reported that the pair met in Cape Town, while Harry was on his gap year, but he revealed in Spare he had actually met her before that, and they reconnected while he was in Africa in 2004.
He discussed the difference in their relationship whilst they spent time in Africa together versus in the UK, where he recommended to Davy she treat press intrusion like a "chronic illness".
He explains that the pair finally broke up in 2010, and the reasons why they felt it wouldn't go the distance: a lack of privacy and believing she would have to change to fit into what life in the Royal Family entails.
"The whole world isn’t made to put up with constant scrutiny, and I don’t know if Chels could bear it, and I couldn’t ask her to," he wrote.
He also claimed that at one time the paparazzi even placed a tracking device on her car, which made her want to put "freedom first".
"Chels insisted that she was not sure if she was prepared for all of that. A whole life with someone on your heels? What could I say to her? I would miss her very much, but I understood she put her freedom first. If I had the choice, I’d want to live like that as well."
Until Spare's release, the relationship between Florence Brudenell-Bruce and Prince Harry had never been officially confirmed.
After what he described as an "idyllic" few weeks with the model and actress in 2011, news of their relationship found its way to the press, and "down came the curtain on our idyll."
Harry also revealed that despite him trying to persuade "Flea" as she is nicknamed to "talk it over", she firmly said no and he later found out from a friend her mother had dissuaded her from continuing the relationship.
"It was Flea’s mother who told her to end things," he explained, "who warned her that the press would destroy her life. 'They’ll hound you to the gates of Hell', her mother said. 'Yeah', I told the friend. 'Mums do know best.'"
Brudenell-Bruce married multi-millionaire Henry St. George two years later.
Harry opened up about his relationship with budding actress Cressida Bonas in Spare too. He explains that the pair were introduced by his cousin at a music festival and that despite the fact that he was "heartbroken" at the time "there were sparks."
During their first date Bonas opened up to him about her life and "dreams".
"She told me about her life, her family, her dreams. She wanted to be an actress. She was so soft-spoken and shy, acting was the last profession I’d have imagined for her, and I said so. But she confessed that it made her feel alive. Free. She made it sound like flying."
Harry also divulged that because of his military career he didn't have much spare time and could only meet up with Bonas during the weekends and that after he returned from his second tour of duty, the couple had to restart from the beginning because he was so changed from the experience.
"Can’t have a reunion with someone you don’t know," he wrote. "If we wanted to keep seeing each other – and I certainly did – we’d have to start again."
Harry also explains how news of their relationship was broken by the press after they had already dated for two years, and how Bonas was the first person he was able to cry with about his mother's death since Diana's burial, something for which he was "indebted" to her.
"Wiping my eyes, I thanked her," he wrote. "She was the first person to help me across that barrier, to help me unleash the tears. It was cathartic, it accelerated our bond, and added an element rare in past relationships: immense gratitude. I was indebted to Cress."
Harry also wrote that when he finally ended the relationship because it wasn't "love everlasting" he thought: "She helped me cry. And now I’m leaving her in tears."
In 2017, Bonas opened up to BBC Radio 4 about feeling "pigeonholed" after being in such a public relationship.
"It’s incredibly frustrating, especially in the industry that I’m in. But you know, it is the way it is," she said.
The woman who would become Harry's wife and the mother of his two children, Meghan Markle, is of course a big focus in Harry's memoir.
In their recent Netflix documentary they revealed that they actually met over Instagram, before embarking on a whirlwind, long-distance romance, which Harry details in Spare. He wrote he had "never seen anyone as beautiful" as Meghan and noted once they started chatting his "thumbs were cramping" he was trying to text so quickly.
Read more: Is Camilla the Queen or Queen Consort?
"I couldn’t type fast enough. My thumbs were cramping," he detailed, "there was so much to say, we had so much in common, though we came from such different worlds. She was American, I was British. She was well-educated, I was decidedly not. She was free as a bird, I was in a gilded cage."
Their relationship went public in October 2016, and a month later Harry released an unprecedented and blistering statement about how his new partner was being treated in the press and online.
"It is not right that a few months into a relationship with him that Ms. Markle should be subjected to such a storm," it said.
The pair married in May 2018 and welcomed their first child, Archie the following year. As the pressure of life in the public eye became overwhelming for the couple, they stepped back from royal duties in 2020 and since living in California, have had a daughter: Lilibet, inspired by the Queen Elizabeth's childhood nickname.
Caroline Flack is also discussed in Harry's new memoir, in which he refers to their romantic relationship as "tainted".
The pair first met in 2009 when they were introduced by a mutual friend, but any sparks of romance between them were quickly extinguished by severe press intrusion that let to paparazzi camping outside her parent's home and deeming Flack, Harry's "bit of rough".
"I continued to see Flack on and off," after the relationship had been made public, Harry wrote, "but we didn’t feel free any more. We kept on, I think, because we genuinely enjoyed each other’s company, and because we didn’t want to admit defeat at the hands of these arseholes. But the relationship was tainted, irredeemably, and in time we agreed that it just wasn’t worth the grief and harassment."
The Duke of Sussex also touched on how he felt when he heard the news that Flack had taken her own life, saying it was "impossible" when he had first known her to imagine this happening.
"She’d been so light and funny that night we met. The definition of carefree. It would’ve been impossible then to imagine this outcome."
He then made a covert reference to Meghan's own fleeting suicidal feelings. "I told myself it was an important reminder. I wasn’t being over-dramatic, I wasn’t warning about things that would never happen."
Although the pair never confirmed a romance, it has long been rumoured that Pinkham and Harry were once involved back in 2003, when the prince was 19 and she was 26.
The pair have enjoyed a long-standing friendship, and in 2009 it was reported that after his split from a later girlfriend, he even turned to Pinkham for advice and support.
Pinkham – a television presenter – is now married to Owain Walbyoff, Managing Director of Endemol Games, and they have two children: Wilfred and Willow.
For a brief time in 2009, Harry was linked to one of Kate's friends, Astrid Harbord. While he was on the outs with Davy he was spotted hitting the town with Harbord in London and they were reported to go home to Clarence House together in the early hours of the morning.
The member of the pop band The Saturdays was romantically involved with Prince Harry briefly in 2012. King admitted the pair had dated after they met at the Asprey World Class Cup, but it was reported that this public comment didn't go well down with Harry, who ended things shortly after.
Another romance from the rumour mill was with popstar Ellie Goulding, after they were reported to be very cosy at the Audi Polo Challenge in 2015.
They were said to be seen snuggled under a blanket together and spotted kissing, however neither party ever confirmed that they were more than friends.