“Sherlock Holmes solved the case before I could, as I recall.”
“Sherlock Holmes is a fictional character,” Trix pointed out.
The Doctor grinned. “My dear, one of the things you’ll learn is that it’s all real. Every word of every novel is real, every frame of every movie, every panel of every comic strip.”
“But that’s just not possible. I mean some books contradict other ones and -“
The Doctor was ignoring her."
Lance Parkin, The Gallifrey Chronicles
this has got to be up there as one of the best quotes of doctor who in any media.