Ok, USB 2.0 adaptor out of the equation and I'm now getting 350-400 megs consistently over Ethernet which is in line with what BT were telling me was my speed to the hub. Hopefully Openreach can work out where the other 500 is going tomorrow. So for now it looks like we're all good thanks so much for all the help and tips, my USB 2 adaptor is heading to the bin!
