The seventh and final Harry Potter book goes on sale at a minute past midnight UK time (2301gmt) on Friday (July 20). Throughout the world, fans are expected to queue at bookshops, hoping to buy one of the first copies. It's a publishing milestone that ends months of fevered speculation among fans over the fate of the fictional boy wizard and his wand-wielding friends. In London, readers young and old are already in line with a long wait ahead. Many have dressed like their heroes for the grand finale of the Potter saga, which experts believe will be the fastest-selling book of all time. Author J.K. Rowling was an unemployed single mother without a publisher or agent 13 years ago, but is now the world's first dollar billionaire writer after the huge success of her first six novels and the Hollywood movies based on them. "Harry Potter and the Deathly Hallows" will hit the shelves in a carefully orchestrated release designed to maximise suspense and sales, from London and New York to Mumbai and Australia's Outback. But it has been marred by leaks of the contents of the book on the Internet, both real and fake, and by a mistake made by an online U.S. retailer that meant a small number of hard copies were sent to buyers days ahead of publication. One of the first to queue in London is Martin Meijer from the Netherlands. It's not the first time he's tried to be first to get the latest Harry Potter book. But on the last occasion he joined a line stretching for one and a half miles. He's ignoring all the spoilers and leaks and plans to read the last book in the series as soon as he gets it. Araventhy Nanthanan, a self-confessed Harry Potter fan, says when she gets her hands on a copy she's going to "scream and run around". Another two fans from the Netherlands, Lenke Hanan and Renee Vloo, says they are just enjoying the experience of camping out in the centre of London. "It's like being part of one big family" said Lenke. But the big question on everyone's lips is what fate has J.K. Rowling in store for Harry? Some fans are resigned to the young wizard being killed off. "It's the final book so he probably has to die," said one. Similar emotions were running high across the Atlantic as Potter fans congregated at "Harry Potter Place" as the countdown began for the release of the last Harry Potter book. In anticipation of the release, an entire block in Soho has been turned into a fantasy land complete with the Harry Potter Night Bus and Whomping Willow. Winners of the Harry Potter Essay Contest were there to begin the countdown. A copy of the first author-signed U.S. edition of the book was placed into the "Pensieve" along with the six other Harry Potter stories. "All the previous contest winners are going to get the free book at midnight and they're going to send us over to a reading room at the Hilton. There's going to be pillows and refreshments and we're all just going to sit around and read, I'm excited," said contest winner Tam Dang, 17, of Woodstown, New Jersey. Another contest winner from Chicago, Illinois named Rachel Johnson raved about what she likes about the books. "They're so imaginative, they're so out there. It's like they combine the fantastical element that, you know, a lot of people really like with the down-to-earth, mundane of the muggle world. It's like this amazing medley and the characters and the plot are so interesting and intense," she said. While the day is all about celebrating Harry, the illustrator of the books, who has worked with author J.K. Rowling throughout the entire series, expressed some sadness. "Harry became just more and more a part of my life, almost like a real person living in my home, you know. Now, as we approach the release of the last book, there's some sadness - it feels like my child is leaving the house and I won't be seeing him again," said Mary GrandPre. The publisher of the series, Scholastic, compared the release of the Harry Potter book to a blockbuster movie release. "Last time we sold 6.9 million copies in the first 24 hours but it does actually continue to sell and in fact the first book, which we published ten years ago is now up to 26 million copies in print," said Lisa Holton, President of Scholastic Trade and Book Fair. It is 10 years since the first book, Harry Potter and the Philosopher's Stone, introduced us to Hogwarts School of Witchcraft and Wizardry. Since then the books have sold 325 million copies world-wide, been translated into 64 languages, and spawned five films.