Barry Cunningham with his copy of The Tales of Beedle the BardCredit:Barry Cunningham It is one of only seven presentation copies of the book in existence, all given by Rowling to the most important people who helped bring her boy wizard to the public.It is conservatively estimated to sell for up to £500,000. The first of the seven copies to be sold, in 2007, went for £1.95million.Mr Cunningham, who now runs his own publishing house, said he would be sad to part with the edition, but that he hoped to use the gift to benefit his children as well as Rowling’s charity Lumos. He spotted the potential of J K Rowling’s first Harry Potter manuscript, signing her up before warning her she ought to get a day job because she was unlikely to make money out of children’s books.But no man could be more delighted to be proved wrong than Barry Cunningham, the editor, who will next month make a fortune after selling his unique bejewelled copy of a rare Potter book at auction.Cunningham, a father-of-six, is to sell his one-off edition of The Tales of Beedle the Bard at Sotheby’s with the blessing of J K Rowling, nearly 20 years after Harry Potter first hit the shelves. JK Rowling, the author, is said to have given her blessing for the sale But, he admitted, he had told Rowling on their first meeting that she may wish to consider taking a second job because “you don’t make a huge amount of money from children’s books”.“She nodded wisely and then sensibly decided to ignore me,” he joked. It contains illustrations by JK RowlingCredit:Sotheby’s It tells five wizarding fairytales left, in the story, to Hermione Grainger by Albus Dumbledore to help Harry Potter finally defeat Voldemort in the seventh and final book, Harry Potter and the Deathly Hallows.The book will be on display at Sotheby’s, London, this weekend before being sold on Dec 13. “It was an amazing and totally unexpected gift,” he said. “It’s absolutely breathtakingly wonderful, and I now want to make sure I can do good with it.”The manuscript is decorated with seven unique mounted rhodochrosite stones, differing with each copy to represent each owner’s personality. To Barry, the man who thought an overlong novel about a boy wizard in glasses might just sell… THANK YOUJK Rowling One of the seven books previously sold for nearly £2mCredit:Sotheby’s It will be sold along with the envelope it arrived in through the post; an unexpected gift which he said left him “flabbergasted”. It is inscribed: “To Barry, the man who thought an overlong novel about a boy wizard in glasses might just sell… THANK YOU”.Mr Cunningham told The Telegraph he had been won over by the friendships in the novel, Harry Potter and the Philosopher’s Stone, believing it would go on to be a “book for book-huggers”. For years, the book was kept locked away in Mr Cunningham’s house, but it has recently been loaned to museums and stored in a bank. Each of the seven books had its own personalised coverCredit:Sotheby’s Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.