Well I've got the old one off after a mammoth effort and what an absolute sod of a job it was to do, I see now why I put it off for so long. In the end the only way was to break the Inlet air pipe off of the Thermostat as there was no way I could get in there to unbolt it, short of taking the engine out. Okay dead easy when its being assembled on an engine stand, but 12 years later and buried in the engine bay, not so simple. Next, without expending an awful lot of effort I'm unsure that trying to get the guts out of the old one would have been that easy, so I've ordered a new one instead in the belief that if that were to last another 12 years/120,000, it'd be the only bit left working on the car . In my spare time I've been playing with a an old FIAT, and some of that is beyond belief, like you have to virtually completely strip the front end to change a Bulb, but in comparison it's straightforward compared to the GV Thermostat .