"Only write what you know" is very good advice. I do my best to stick to it. I wrote about gods and dreams and America because I knew about them. And I wrote about what it's like to wander into Faerie because I knew about that. I wrote about living underneath London because I knew about that too. And I put people into the stories because I knew them: the ones with pumpkins for heads, and the serial killers with eyes for teeth, and the little chocolate people filled with raspberry cream and the rest of them.