OK So I have numbers now...
Cold start, I get 3 bar (45psi) which if revved a bit to 1500rpm goes to about 3.75bar (55psi) and then doesn't climb. So I guess the pressure relief valve is working OK
After a short drive and the water temperature needle is just lifting off the bottom, I get about 1.5bar(22psi) at idle.
After it's up to temperature and I've done a few miles, I have 1.1bar (16psi) at idle, 2bar at 1500rpm and 3bar at 2200rpm etc.
Does that 1.1bar on hot tickover look a bit low? I've no idea what they should be I've not found any references to correct pressures for the engine in the overhaul manual.
Thanks.