I'm gobsmacked.
Many thanks for taking the time to do that just on my account. Really appreciated.

Your photo has given me a good clue; I see that you are using B.2 and B.3. Up til now I'd been using B.0 and B.1 only.
It turns out that it only works from B.1 onwards (with both PBP *and* LCD_AnyPin). I thought it might be because of a hardware fault, but B.0 is fine with a temporary LED.
It's all rather strange because the PBP manual implies that any PortB pin should work.

Do you mind if I trouble you for one more question, pse?
Could you have a look at my CONFIG and perhaps let me know why MSC gives an error when I try to compile without the semicolon?

Thanks again to you for doing all that work on my account.