Sorry for these endless posts talking to myself, but I have now identified the actual cause.
Remember that my neighbours broadband is really suspended and this is key to the whole thing, and the other symptoms I have been seeing also explain everything.
So, my neighbour is currently using my broadband via WIFI,
I currently see 16 devices connected via wifi to my smarthub. However, earlier on when I went to the hub homepage I could only see 2 devices on wifi which is obviously not correct.
So something next door has created a bridge between our networks, and at this point I am guessing its the main SKY Q box being connected to my WIFI and an ethernet cable going to their hub, so it has in effect become a router.
So I now have two BT smarthubs with the same IP address on my network, this would explain everything. Some of our web requests are being routed to the suspended smarthub, remember it has the same IP address and there would appear to be no duplicate IP address checking in the smarthub firmware and that the smarthub is the default gateway.
it would also explain why sometimes when looking at the smarthub, trying to enter the admin password would say it is incorrect and 5 mins later it would be ok as the login request was going to the wrong smarthub.
I could change the IP addressing on mine, but it would break to much my side, so my neighbour is instead just going to unplug the suspended smarthub which should solve the problem, I'll let you know. Who would have thought the Sky-Q box even allowed routing across its interfaces.
