After a media onslaught of interviews, trailers and leaks, Harry's memoir is published
Fans queuing to buy a hardback copy described wanting to hear the story "from the horse's mouth".
It follows the chaotic launch of Spare with multiple leaks and copies being made available in Spain last week.
Waterstones says Prince Harry's book has been one of its "biggest pre-order titles for a decade".
The booksellers opened their flagship Piccadilly branch early on Tuesday in expectation of high customer demand, as the book was published around the world in 16 languages.
Branches of WH Smith in locations including Euston, Victoria, Heathrow and Gatwick were also among those to extend their hours for the release.
The memoir is already top of the best sellers in the UK for online retailer Amazon, after days of headline-grabbing revelations from leaks - ranging from how Prince Harry lost his virginity to claims that Prince Harry was attacked by his brother, Prince William.
The 410-page memoir, revealing the conflict and personal tensions inside royal palaces, shows Prince Harry's version of growing up and then falling out with the Royal Family.
So far Buckingham Palace and Kensington Palace have not responded.
But the claims in the book include that Prince Harry begged his father not re-marry, that he killed 25 Taliban fighters while serving in Afghanistan, that he took psychedelic drugs, partly in response to panic attacks, and that Meghan and Catherine had a difficult relationship.
The book paints a picture of the brothers, "Harold" and "Willy" being in conflict
A major theme in the book is the sense of unresolved grief for the loss of his mother, Princess Diana, with Prince Harry saying he had a "post-traumatic stress injury".
The press are held responsible for pursuing Diana and Prince Harry said in one of several interviews promoting the book that it would be his "life's work" to change the media landscape.
There are also unexpected details such as Prince Harry and Prince William calling each other "Harold" and "Willy", that Harry used to get his clothes at discount outlet TK Maxx and watched a lot of Friends on television.
Prince Harry recalls he first found out from the BBC website that the late Queen Elizabeth had died, rather than from his family.
The revelations about tensions with the Royal Family, including Camilla, the Queen Consort, and the Prince and Princess of Wales, has provoked much controversy.
Despite the leaks, many queued late into the night to buy the memoir.
Professor Chris Imafidon, from Epping, was in line at Victoria Station and said he was "extremely curious" to hear why Harry had stepped back from royal life.
"I really want to know from the horse's mouth," he said.
Also in the queue was bartender Sasha Pursell, 27, who has moved to London from Melbourne, Australia.
"I'm just intrigued," she said. "I've heard so much press about the book and it's also just a bit exciting - I've never been to a midnight release."
And Sarah Nakana, 46, from south London, said she had already downloaded the audiobook because she wanted to try to "get ahead of the British press and their narratives".
"I was just like: 'No I just need to cut the noise here, read it and be like, 'fine, I can move on now,"' she said.
Reporters and photographers gathered round the first customers at WH Smith
Opinion polling from YouGov, published on Monday, showed an initial dip in Prince Harry's popularity in the UK.
There were 64% of people who had a negative view of Prince Harry, compared with 26% who had a positive view of him, down from 33% in the autumn, and the lowest figure in more than a decade of this regular survey.
Five years ago this tracking survey, based on a sample of about 1,700 adults, showed 80% had been positive about Harry.
But the latest figures for January 2023 showed more support among young people, aged 18-24, with numbers almost evenly split between those with positive and negative views of Prince Harry.
-- Courtesy of BBC News