Ideal Classic No Heating?

I have an Ideal Classic RS50

The heating went off overnight, pressure went down, so bled the radiators, lot of air and refilled and pressure now just above '1'

Pilot light is lit but no heating

Have checked and moved the thermostat / room temp control and can hear it click as it gets past 15, but still no heating

Checked the controls in the airing cupboard and lights are lit for Water and Heating, Seems I still have hot water,

any ideas on what could be the problem??