"Not enchanted by the break with convention in so many of the clues where half of the abbreviation (eg N in Nova Scotia) becomes the extra letter."
I'm not sure whether it represents a break with convention since extra letters generated from two-letter abbreviations are not uncommon in the Listener, but I agree with Caphrist's objection, and I think it's poor practice. A similar thing I dislike that's found here is an extra letter generated by a short word that is already shortened by the clue, leaving only half of the original word in the answer, eg, 6a, 16a, 42a. It doesn't break any rules, but it seems an inelegant way of making clues difficult.