JKR [in her office]: It was five years from the train journey, where I had the original idea, to finishing the book. And during those five years this massive material was generated -- some of which will never find its way into the book, will never need to be in the book. It's just stuff I need to know for my own pleasure -- partly for my own pleasure and partly because, I like reading a book where I have the sense that the author knows everything. They might not be telling me everything, but you have that confidence that the author r