Ahhhhh he has resettled!!
Update:
He resettled at 1340 and woke at 1505 so his nap was 2hr25.
He seemed tired this afternoon so decided to do 1915 instead of 1930. I think he got a second wind (I seriously doubt he is ut), and only fell asleep at 1930 with WIWO. Maybe I should have tried 1900? On the one hand I know I need t stick to the same BT for a few days to really know if it is working or not, but he is so obviously OT he probably needs a shorter A with such a long morning A.
I think I will try DM tonight just to check fi it makes a difference...