OOPs thanks to those of you who pointed out it was not Bearmach but BRITPART who dont sell thermostats at shows, even when they have one. (I have ammended the origional post)
Four of us did go round the other stalls but no one had any, except BRITPART.
The problem with running without one is that the housing wont seal without one, it has a rubber seal that sits between the housings and also the bottom button on the thermostat diverts the water flow to the radiator when the engine is hot. If you take the center out, the water will take the flow of least resistance, which I guess is round and round the engine and not via the radiator. Well at least it appeared to up birdlip hill, must find another way home mmmmm up to cumbria across to leeds and down the m1 now theres a thought