Posted by Parallelogram in wrong thread and moved at his request
I have been a bit exercised by the clue which referred to "the last across clue" in its own definition. It seems that the setter was referring to the clue immediately previous to the one containing this phrase. My gripe was that this is not how last is used generally because, in solving a crossword, I imagine that very few people begin with the first across clue and continue with the next one only when the first one is solved and so on down the list of clues. In those circumstances, the solver will not have experienced the final across clue when solving the problematic one and so the use of last to describe the preceding one is appropriate as it was the last one the solver completed. An analogy is with the term "last week" which everyone understands because they have not actually experienced any future weeks. This, however, does not match most people's experience and last will clearly mean the final item in the list.
Having said all that, what I really wanted to do was recall a story about a former music teacher colleague. Each week of term, he posted a notice listing the times of individual pupil instrument lessons, clearly identified as Week 1, Week 2 etc. Until the final week of term when the list was labelled Last Week. He could not see (at first) what I was laughing at when I pointed out the ambiguity of his notice. I also don't think he ever changed what he was doing. I suppose there might be a subtle difference in emphasis of the two words that denotes the difference.