Thank you Throck. I've now checked out the entry for 'mill' and can see what you mean. I was keen to stay within the SEARCH AREA, but who knows?
There have been some interesting suggestions, but nothing seems entirely convincing. For instance, I could just about see the 13 cell 'illustrated' hare, but mine looked better the right way up with its paws outstretched (seeing the head as a tail).
I particularly like the suggestion that the line in the preamble, ''...in a straight line'', means the highlighting must be in the grid, otherwise it's completely redundant and, even worse, misleading.
The advice to dump the whole thing and not get too deeply involved appeals too.
I can't say I've enjoyed this one. If I'd managed to hit on the right solution in a couple of hours (as some appear to have done) I'd feel differently, but with all of the hidden elements here It would require a genius I don't possess.