Ok, reinstalled on a new SD card.
I now have ...
Kernel 4.9.35-v7+
PAW Version 20170721
Looking at the network info under the newly setup PAW network, it is still showing 192.168.1.1 as the router. Attempting to connect to my iPhone hotspot via Bluetooth, it attaches but seems not to want to communicate out that route, presumably because the iPad thinks the PAW is the router, and the connection shows 'no internet connection' again indicating it believes the wifi network is the gateway.
So, complete new PAW image, new network setup ... doesn't appear to work as expected...??
Edit, scrub that, just done an iPad reboot and it now does appear to connect happily via my BLuetooth hotspot ...