I just wanted to say to all you puzzle solvers on this post that I am sincerely sorry if I ruined the fun for blurting out what I thought was the answer. I was so thrilled to think I had solved it, that I didn't think about that possibility. I tried to erase it, but it will no longer let me edit that post. Again, very sorry if that was the answer, but crack on fellow puzzlers! My hat off to you!
EDIT: no worries, thanks for your concern - added the spoiler tags above - welcome to the Den Chronic. - plainglazed