Rest in peace Diana Wynne Jones, who passed away on 26 March 2011.
Two quotes from the Tor site say it best:
She was passionate about what children want and deserve from their literature. Adults would approach her at signings, wanting to know why she wrote such difficult books. In one case, when a woman protested, the woman’s young son spoke up and assured Diana, “Don’t worry. I understood it.”
Emma Bull, Remembering Diana Wynne Jones
… meanwhile Diana’s readers, children in 1973 when Wilkins’ Tooth came out, were grown up. It would be conventional to say here, “and had children of their own” but while that’s true too, what is fascinatingly true, is that many of them had books of their own. Diana had not just grown fans, she had grown writers.
Farah Mendelsohn, Diana Wynne Jones
You were the best, Diana.