D’oh! When the penny dropped it did so very hard. A very neat twist. Thank you, Artix.
Thank you also to Simplesimon for trying to help me, but I was too far down a warren of rabbit holes chasing wild geese in mares’ nests at that stage. Putting it aside was, as so often, the key. Standing at the ironing board this morning listening to R3 and the essential ambiguity (not the “which title” one) was suddenly illuminated.
For what it’s worth, I am going with the second title in the final grid, That seems the straightforward reading of the directions.