Cured, cured and 3 times cured
It was the fault of the first replacement thermostat.
I tried pot testing it and did not see any movement.
Ordered another from euro car parts to do a comparison.
Pot tested that and again nothing.
Thought well I've bought it so may as well fit it.
Ran engine temp hit 90 top hose went lovely and warm. Few mins later rad fan kicked in and temp was maintained for an hour.
Faulty or incorrect thermostat was BGA CT5626
Correct and working was a Calorstat by Vernet TH6824.88J. came with gasket and new sensor and after bank holiday promo discount code online was £28. Great
Thank you so much forum. Gave me the confidence to keep going.
Only downside now is engine management light now on but fortunately my son in law carries the necessary laptop and plug for that. On to the next issue!
Thanks again. Hope this helps others.