Is there a natural gas detector available for domestic use? Friend's elderly mum is absent-minded rather than suffering from dementia etc. but occasionally leaves the gas hob unlit, causing gas to escape. Is it possible to fit a device to the hob so that this can't happen anyway? Or are there new hobs now that have such devices as standard that could be fitted? Ironically, she has a shiny new (plug-in) electric oven beneath it but my pal doesn't think that her electrics would be up to having an electric hob too.