The weather alters how my heating works, may seem odd, but if very cold heating works better than when just cool.
I know the problem, it is where the wall thermostat is installed, in the hall, about central to whole house, on the wall between doors to living room, dinning room, kitchen, and shower room at bottom of stairs.
Being central it is last to cool or heat, and the hall radiator is about 9 foot away from wall thermostat, and the TRV set to lower temperature, heat raises, and TRV at bottom of radiator.
House is allowed to cool over night, and in the morning the temperature is increased 0.5°C per hour, this means in really cold weather the boiler fires up at least once an hour, for first 4 hours, but the hall cools slower than any other room in the house, so living room getting chilly before the hall has cooled enough to restart boiler.
All rooms but toilet have electronic TRV heads, but clearly they can't heat room if boiler not running.
I think half hour is shortest time between temperature changes, looking for setting ideas.