I should have also said that the only way to restart the heating is to turn the thermostat to a higher setting.
Yes, it is as if, when the house reaches the the set temperature, the heating is switched off.
You seem to have missed the point, in my initial question I said that when the desired temperature is reached and the heating turns off, it never comes on again even when the rads are cold.
I have already told you that I do not have motorised valve so we seem to be going round in circles here.
Forget it I will sort it elsewhere.