This morning very early, dark, when Mrs J went to work she let him into the bedroom (something that normally happens, albeit a bit later). I half woke up to hear him rustling into things under the bed, and mewing plaintively. As he is deaf, I had to get the torch out and rescue him.
He has a path whenever he is let into the room, he goes right round the bed, jumps onto Mrs J's side, then clambers over her to get under the covers with me. Quite unlike him to go under the bed and get lost.
When I got up he was same as always, finding his way about. So my current diagnosis is he has lost night vision. His weak kidneys mean blindness is always a possibility through high blood pressure, so he is on tablets. We know that the kidneys will gradually get worse, he is 17 next week.
I think he needs a vet check-up next week.