How to Authenticate a Signature of CS Lewis

I've had a dream of buying an old lumpy chair at some antique store and going to refinish it and discovering that it was stuffed with wadded papers written by Charles Dickens or Charlotte Bronte. So that is a story that really comes close to my mind. My team is I'm digging around the Bodle and I find the Stusteel volume and it's the red book of Tolkien and all this really was written down after all. He always claims he was just doing research into Middle-earth. That would be quite a find, I think. Yeah, it would.