Well I was at home yesterday when the snow struck.
Thought to myself a while later "this house is getting a bit cold" - went to the thermostat to turn it up.
But it was already calling for heat. Radiators stone cold. Look at Boiler, pilot light out.
Try to relight pilot, it relights. Turn boiler back on and within a few seconds the flame dies down and then goes out.
Go outside, flue is covered in snow! GRRR!