Although Jk Rowling has already declared that it will be the final chapter in the ‘Harry Potter’ series, she might be tempted to think twice after reports of sales of the newly-released ‘The Cursed Child’ set to make it the biggest-selling book of the decade.

The special rehearsal edition of the book form of the script, featuring stage directions used by the cast, went on sale for £20 in hardback on Sunday (July 31st), and it’s been absolutely flying off the shelves around Britain, with more than 680,000 copies sold in the first few days, according to Nielsen BookScan.

JK RowlingJK Rowling's new 'Harry Potter' script, released in book form on July 31st, looks set to be the biggest-selling book of the decade

The edition currently available is set to be replaced with the definitive edition, to be published in early 2017. It will include final stage directions, annotations and other extra content to tease fans, so the book can expect another massive sales boost to add to the already impressive figures.

The previous record was held by ‘Fifty Shades of Grey’ in 2012, with 664,478 copies sold in its first week.

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Set 19 years after the last actual novel and following the story of a grown-up Harry Potter, the play opened officially on July 30th, after nearly eight weeks’ worth of preview shows. Producers recently announced an extra 250,000 tickets that will become available from August 4th, at 11am, for shows running all the way up to December 10th, 2017.

Kate Skipper, the director of purchases at Waterstones, told the Daily Mirror that she expected it to easily be the biggest-selling book of 2016, and quite possibly of all time.

“Our sales have been phenomenal; we saw our biggest first day figures since ‘Harry Potter and the Deathly Hallows’ was released in 2007 and after just two days' sales ‘Harry Potter and the Cursed Child’ is already our biggest-selling hardback since Dan Brown's ‘The Lost Symbol’ in 2009.”

“By the end of this first week, we expect to exceed 'The Lost Symbol' sales and to match the lifetime sales of our bestselling script book ever, ‘An Inspector Calls’ by J. B. Priestley. There's no doubt about it; this will be our biggest book of the year.”

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