Now I can post freely I can update this thread.
I suspected the inlet manifold water temperature sensor was the reason for the over fuelling, cold temperature gauge and high idle speed so nipped to the Mini Spares Centre at York to buy a new one. However before it got swapped I was talking to a mechanic who works part time at a mates garage about it, who it turned out served his time at Austin Rover and used to work for a mini specialist in Leeds, so new is my new best mate.
He'd done some work on it for my dad a few years ago and said flush the water system out first, we did and he was right had some 'crud' in it. The idle speed dropped, the temperature gauge rose and all returned to normal. So I got it mot'd for only the second time in the past 11 years and it passed with no issues.
The next thing on the to do list is put a set of tyres on it as although it has done less than 4k miles in the past 25 years it is on the rubber from 1994 when it had new wheels and tyres fitted. But with a summer holiday, a pair of tyres for the wife's car and a house extension to fund the mini is at the back of the spending list for now.
Edited by PH5121, 30 July 2019 - 03:17 PM.