Incredible as it may sound, J.K. Rowling's compendium of seven Harry Potter books is no longer the best-selling book series on Amazon UK — that crown has now been passed to E. L. James' monumentally popular Fifty Shades of Grey trilogy. James' books have sold over four million copies in print and on Kindle since going on sale in March 2012, making her the most successful author of all time on Amazon's British portal.

In terms of individual books, the first novel in the series, carrying the titular name of Fifty Shades of Grey, has been outselling Harry Potter and the Deathly Hallows by a factor of two to one in recent weeks, which has resulted in it becoming the all-time bestselling book on Amazon UK. Amazon also tells us that Fifty Shades is comfortably topping the bestseller chart in both print and Kindle editions in the US, but it doesn't seem to have yet managed to break any records the way it has in the UK.