Quoting CharlesElliott: If you have no bypass hose, that's fine as long as you don't have a thermostat either. Is it an ex-race engine? They are often like this.
Ah, ok - that could explain it then. The previous owner used it for sprints and hillclimbs, maybe he removed the thermostat . Now you've said that I'm sure Dave Walker commented that it either didn't have one or it wasn't working when I was up there.
Is there an easy way of telling if one is fitted or not? Would there be any difference in temperature behaviour - for example the water temperature never seems to get that high unless I'm sat in traffic for ages but on the move it seems to run quite cool or is that nothing to do with it?!