Yes but according to a quick google search it just says as long as it doesn't dazzle other drivers. I suspect lots of the ones that dazzle are poorly designed cheap imports.
These may be suitable
https://www.classiccarleds.co.uk/products/d1s-hid-to-led-conversion-kit-8600lm-6000k-daylight-white-replacement-for-oem-hid-zenon?srsltid=AfmBOoocbQoTrI3t-1naHRnzJWjPFqYte_Vr_m6mw8JXqvKw3Ab5SNbQ
So the insurance company will say you shouldn't have been driving it until it had been assessed. Sadly I think you'll have a job proving you didn't cause the issue.
Just to be clear. And I know now't about this model.
6 months ago you were getting white smoke so parked it up.
Then someone reversed into it so insurance company sent it for a quote.
£14k for new engine.
What about bodywork repair?
What have insurance company said?
For typical LEDs then yes I agree but the LED voltage regulator may be set higher than 10v. I'm no expert on car LEDs but they may have a cut off voltage to stop battery drain with the ignition off. A quick google of a LED bulb gave Supported Voltage: DC12-17V.
My thinking is that the engine will turn over with low battery voltage i.e 12 volts but the LEDs may require slightly more to fire up.
My TD5 Disco would fire up no problem with low volts but it wouldn't rev as the ECU didn't like it.
Worth checking the voltage at the battery and at the bulb IMO...
The FBH should only kick in below around 6 degrees. As you say the thermostat would be my first choice.
Looks like it maybe the thingy @gold rover was talking about.