Every day brings news of more and more projects hanging onto Fifty Shades of Grey‘s coattails (or cat o’nine tails). You can’t blame any of the bandwagon-jumpers, though. E L James’ S&M trilogy is quickly joining the likes of Twilight and The Hunger Games in terms of sales, and Amazon UK has reported that the books have become the best-selling books in the website’s 14-year history, overtaking the Harry Potter series in just four months.