Thanks for the earlier replies ref the thermostat, will check it out in the morning.
The only other problem with the car (which is otherwise in great nick for under £3k!) is that I can't engage the diff-lock. The lever won't push across at all and I wonder if it could just be seized or is it likely to be more serious? The transfer box was stiff when trying to engage low range but after a few goes it has freed up a bit. Any help appreciated.
Andy