Gosh. I came here looking for hints after getting stuck after just four clues. Which, interestingly, already included the troublesome 18 :-). But all I find is everyone saying how straightforward a solve this one was!! I shall go back and have another look with fresh eyes...
Thanks, but I was looking for hints, not answers. I’m glad the other thread exists for those who want to ask for, or want to give, more explicit explanations. Fired with renewed determination, I went back to work and finished it the same evening!