" Unfortunately, no one knows what they are."
W. Somerset Maugham
There's a little more substance to the 'Rules for Writers' found here. Hilary Mantel's look sound; Sarah Waters lists hers and then says, "Talent trumps all. If you're a really great writer, none of these rules need apply," while Elmore Leonard presents his in book form, and sums them up thus: "if it sounds like writing, rewrite it."
In the chapter 'A Talk about Rules' in Reflections On The Magic of Writing, Diana Wynne Jones discusses the way rules for writers constantly change, and so instead of rules she adopts her own principles, the first of which is "you have to be responsible. By that [I mean] that somewhere, somewhen, someone is going to read your book at a time when such things stick for life. And you have to make it the kind of book that is worth remembering that vividly for that long. You have to make it an experience in its own right."