Finding the question and its author requires reading one of the instructions to the base of the thematic number [this line of thinking also reveals why Z=20]. The clashing letters hint at an author one of whose books 's titles is a number, famously containing a striking example of the thematic number. So I think, anyway, but I have to admit to being quite stuck on the shapes, as well as the reference to C clashes and the BBC edition of the dictionary.