OK, had a look tonight, got a new t'stat, but found a new 1 already in there! a small amount of gunk is in the expansion tank, but that looks like a the 'dog doo' type of rad weld!?! Refitted the t'stat that was in there, refilled with water, & ran up; took a while 2 warm up then the temp guage shot up to 1/2 way & stayed there! Checked the expansion tank was ok, top of rad was HOT but bottom hose was warmish, then the expansion tank started to bubble so i switched it off!
I'll do the hydrocarbon test if i can get it to work, but i think it's going to be a head gasket now!?!
Is it a hard job 2 pull the engine out?

Phil.