So just to update and close this thread.
Ordered the relevant thermostat from the local auto factors (82 degree unit) and installed it at the weekend. A reasonably straightforward install
(have to admit I found this youtube invaluable: https://www.youtube.com/watch?v=TrNG5z0vUcw&t=415s )
and the nuts on the tube on the manifold from the air pump valve loosened with just a little spray of penetrating spray.
So I am glad to report that the replacement of the thermostat appears to have solved the over heating issue. (I suppose it does not seem like there is an issue as the only indicator is that the cooling fans are running at full blast - because the temperature gauge seems to happily sit just below centre irrespective of temperature!
Using an OBDII Bluetooth adapter I monitored the temperature and I never seemed to climb above about 93 degree C - this was just sitting - no driving - however a quick drive (speed slow but revs up a touch!) and at no stage did the cooling fans come on - before this after two or three mins they would be on - and persist as the temperature would not decrease.
I hope I have this solved - my only concern is what other damage has been done because of this issue and when will it raise its ugly head - and I do not know for how long it has been like this oh well I am sure time will tell but for now onto the next job - new discs and pads all round!
Thank you to everyone who has contributed and helped solve this first problem - ( I suspect one solved of many to come )