HI Martyn.
Your first port of call is to find out what the true temp of your engine is, take the car for a 10 miles drive at low and high speeds, before you start your journey set the IPK using the 19-7 test.
Doing this will give you the correct temp of your engine, the dial for the temp which is usually at 9 o'clock makes no difference if the engine is at 75c or 100c.
Once you have set the IPK to 19-7 go for at least a 10 mile drive with this set you are looking for the temp to be around 85c 89c for a good working original thermostat.
If the reading come back in the 75c to 79c then the original stat is most likely opening early and your car would benefit from a stat inline or a original changed one.
https://youtu.be/OcB5WLEPdL8
https://www.the75andztclub.co.uk/for...ad.php?t=55585
Then go from there my tourer gets up to temp after 4 miles 88c i have an inline gates stat, and no FBH mines in the shed keeping me warm in there