I'm going to give some hints. The author is British. He is knighted. Though he was diagnosed with Alzheimer's in 2007 he is still writing and his 39th book is due out next year. For Halloween we made our children practice saying "Crivens" and "Wailey, wailey" One of my favorite characters in the series is Horace the cheese and I was going to make my son carry around a block of cheese with a tartan on it but we recently had to take him off dairy and I knew he wouldn't be able to resist eating it.
If no one guesses by tomorrow night I'll give the answer and choose a random winner from among those who guessed. YOU MAY GUESS MORE THAN ONCE! So take a look at the clues and keep guessing. You can guess on this post or keep guessing on the post below that has the pictures.