tiggity,
Gas central heating of most types requires electricity. The controls are electric, and more importantly, so are the circulating pumps.
Now your stored hot water will work without (until it runs out), so long as there's electricity for the water company to keep pumping mains water at you. There, you do have an advantage over a combi-boiler, which heats the water as you use it.
Although thinking about it, the UK doesn't force combi-boilers on anyone - do you actually mean condensing boilers?
Biting the hand that feeds IT
