Now I don't like to be pedantic (LOL!) but I believe what I have always called gasometers as Dave does, are officially gasholders. Unrelated trivia thread creep: I understand the ones by King's Cross station in London are being demolished for development of the site and then re-erected afterwards as listed industrial heritage structures, though no-one knows what use to make of them!
RtS( who was brought up within sight and smell of Saltley gasworks in Birmingham so this song has always held resonances for me).