Yes! - you know, as I typed the author's name, I was thinking to myself, "Maybe Trevor the toad is more significant than we have thought?" ;)

BTW, if Trevor's book is a conscious influence, it may give support to my friend's theory that Neville, not Harry, is the chosen one. In that case, Harry, like Cecil, would really be the catalyst for the action, not the protagonist. But Harry really feels like a protagonist to me, and I have a feeling that, though Rowling may have read this book as a child, any influence it may have had on her work is unconscious.