sounds like a thermostat problem, it is not shutting off at the right temperature so your overheat kicks in.
cant remember what boiler you said you had

BG MIKE

Glow-Worm Space-Saver 40B MK11.

It ran for 15 hrs overnight (on the very lowest setting) before cutting out. I restarted it again at 07.30 hrs this morning and it is up and running again (still on the very lowest setting).

I didn't think that this particular boiler had an overheat?

Somebody has suggested recalibrating the thermostat (Ranco), is that possible, or am I better fitting a new one?

RSD, November 2006

some did have an overheat but others did not, if it does not have one then the fact the thermostat is knackered would not make the pilot go out, are you sure the flue is clear?

BG MIKE, November 2006