Actually @Australis I think you should set it in Cornwall. You'd have beautiful scenery, a beach to fall back on (and maybe the living fire can EMERGE FROM THE WATER at some crucial, horrifying moment) and you could have that whole backcountry abandoned by London vibe. Rural nouse needed.
You can thank me for this idea by having fireys scoffing down teacakes while sooting up the local.
Hahaha..... I like the notion of the fire coming out of the water. That actually would look cool and horrifying.