Hey there
I beleive that in Law you will find that the Gas Company owns the gas meter and the sundry pipework to the same including the isolating gas valve of which you speak. Their property includes but is not limited to the gas valve, the pressure regulator (governor) and the meter.
The property owner’s costs begin at the outlet of the gas meter and in some areas they are also responsible for the gas pipe from within their property boundary line up to the isolating valve at the inlet to the gas meter.
Hope this helps.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians