Well after a long day fannying around I managed to try different setups. First I tried running the engine till it was hot (up to 110C). Turned out my temp gauge reads just over 90 when the Ecu is reading 106. I know the gauge in the car is accurate as I had itin a pan of simmering water and it showed 98c. So, when I ran the engine up the gauge in the car didn't get past 95 so it's obviously not over heating. When I floored it it did cool down rapidly to 80 so maybe I still have a strange thermostat. I'll buy the caterham one at the end of the month and see how that fares.