Series 1 Discovery overheating problem

[Rubbond]

Is this a Sunday morning quiz Kevin?
You didnt say which Disco and which engine.
My Disco II TD5 did this last year. Annoyingly it also has an idiot-proof
electronic cut-out device that leaves you crawling along or stuck on a
railway crossing if the engine overheats. Worse still, you can only follow
the top hose to guess where the thermostat is, you can't see the housing let
alone where the bolts are located.
Remedy - yes, the garage.
Leaving out the thermostat for a while in my opinion can't do any harm, but
you're likely to forget to put a new one in later. I often leave them out on
old outboards, where cooling channels are usually furred-up and the
thermostat causes a huge obstruction to flow even when they are open.
If you leave yours out surely the engine will just take longer to warm up,
so just don't drive off immediately if it's very cold. Certainly better to
drive to the garage without the engine overheating, if it will let you.
I would image anyhow that the engine management system would use the
temperature of the engine oil or the engine block itself, wouldn't it?
Good luck!
Andy.
PS Those blogs can be very useful, but like my postings, 50% or more are
rubbish!