Today we played detective and "hunt the missing thermostat". The temp gauge has never come off the COLD stop when out in the car.
There are at least 3 thermostat part numbers, each has different temperature curve resistance characteristics. I have tried all 3 and none did a darned thing. Earthing the wire to the temp guage at the sensor end makes the Gauge read "H" and beyond.
Yesterday a chap on the mini forum declared that my 1275 based engine and SMITHS binnacle package would most likely use the GTR101 thermostat (the one I actually have in it at the moment and that doesn't move the needle away from "COLD").
So, I pulled the thermostat out of the head clipped an earth lead to the outer casing of it and placed it in a cup of just boiled water.
Hurrah! the gauge lifted off the stop and towards the "N"ormal position. I pulled it out of the water and applied a blowtorch cigarette-lighter flame to the thermostat for 15 seconds. Jumped back into the car to see the gauge had climbed to just below the "H"ot position.
My original theory that there was no thermostat in there and therefore the oversized radiator with permanent water-pump maximum flow and a belt driven fan was keeping the water too cool seems to be about right to me.
An 88° thermostat is on order and expected next week.