Close to giving up. Tried everything, loads of soap on the rim and bead, 180psi in the tank. Still not enough to seat the tyre. Tried a mates small compressor, same result. Going to pop down the LBS to give their big compressor a go, but if I need to do that each time I want to fit a new tyre then I’ll be sticking with tubes.
I’m a bit surprised really as while the tyre is bloody hard to get on the rim I can still manage it with encouragement from a tyre lever, so can’t be that tight.