Yes, the pump is spinning.
The boiler is a Potterton Netaheat. There are two tanks in the loft, the smaller one is definitely for the heating system. I've now found that the boiler does fire up for a minute or two when I switch on the CH from cold.
My heating system has stopped working completely after I bled a couple of radiators today. The symptoms are that the pump is very hot but the boiler is not firing up (not even attmpting to) and obviously all radiators are cold. I've checked the tank in the loft and it's full. Before bleeding the...