Cooling System again

Another major breakthrough this morning, I think :-)
For almost 3 years I have suffered with overheating problems and water loss, and each time I have fixed something I have proclaimed it has been fixed only to be subsequently proven wrong.  But ever since I repaired the joint in the cooling system pipes, uprated the radiator cap to 21psi, chucked a tin of radweld in the radiator and re-fitted the thermostat, she has stopped leaking and overheating.
Unfortunately she was now running much too cold, such that the temperature gauge on the dash hardly registered.   And as I have access to a digital readout I could see that the ECU had her stabilising at 143F (62C), at least 30C below what she should be. First port of call in that situation is the thermostat (some of us are old enough to remember stage 2, which is a piece of cardboard across the grill:-) ) and I was still using the original thermostat.   So treated myself to a decent 88C Thermostat from Rimmer Bros, an acknowledged good firm for MG Rover parts.   Cost £20 inc P&P but I didn't want to skimp.
Fitted it this morning, and was pleased to see that when I took off the thermostat housing the cooling system was still full.  Last time I put any water in was about 3 months ago.:-)   So out on the test run.   She warmed up to 195F (90C) very quickly (right in the middle of the green on the ECU Gauge and on the 'O' of Normal on the gauge) and then stayed pegged there for the rest of the trip. Interestingly, although the ECU sensor temperature readout (which is below the thermostat) was solid, the car gauge (which has a sensor above the thermostat) did wander a bit from just below the 'N' to just above the 'M' of NORMAL.   It is obviously very sensitive and shows the thermostat opening and shutting.
Sitting back in the garage with engine idling she drifted up to 220F(105C) (Showing on the 'A' of NORMAL).  Technically above boiling point but being pressurised that didn't happen.  But when the fan was switched on she went back down to about 200F (91C).
So once again I am pronouncing her fixed.  Although time will tell, I am quite confident this time.    Remains to be seen what happens in the heat of summer.   Maybe I will need a 'summer' thermostat (75C?) and a 'winter' thermostat