The cover looks like it must be a John Howe illustration, though I haven't yet found the small print that says so. However, in the booklet I did find that the introductory words are written by:
Brian Sibley!
edit - I found the small print. It is by John Howe.
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'Mercy!' cried Gandalf. 'If the giving of information is to be the cure of your inquisitiveness, I shall spend all the rest of my days in answering you. What more do you want to know?' 'The whole history of Middle-earth..
.'