Re 6d, Grim @ 89 and following discussion: my memory of A level chemistry is the same , I thought the word in the clue strictly meant a high-pH corrosive substance which the answer is not. It was a write-in with that misgiving, but I said to myself ‘I wonder what Chrise will have to say?’ I don’t think we’ve heard from Chrise this week, I hope all is well
There was an early question about the passing of 21a that I don’t think was answered, it splits 1-1-6 but I’m sure the asker worked it out before long.
I’d hoped 14a and 23d would give a more interesting medieval theme, I feel we’ve had the actual theme too often before!