What a nightmare that was!!! I now have a full grid and a headache - but I still need to fill in the diagram, which I think will be another hurdle yet to cross. As the better half is insisting I do some gardening, which isn't helping, I shall return to this later today, and probably tomorrow as well. Some of the clues, and the misprints, were in my opinion bordering on unfair, but just to the right side of it. Having "trigger" for 13ac proved rather distracting - but then again, I couldn't parse it properly anyway.