Thanks but yep, got it sorted.
I did try US automotive and somewhere else, name escapes me, managed to fine the "correct" one in the US, one of 2 available in the whole of the states! Cost, about £600...
The sensor is a thermocouple that feeds into a circuit that just puts a cat overtemperture light on the dash! One supplier gave me some info on how to use a resistor to "bypass" the sensor and put the light out. I did some reserch and found an exhaust temperture sensor on ebay for £15. This was just a thermocouple, did a bit more research on how to wire it up. A bit tricky as a themocouple isn't a switch, it inputs a signal into am amplifier circuit so it had to be the right way around! All back in the exhaust pipe and warmimh light off!