Well, for one, when one quite clearly 'Reply' s to another's post, it is also quite clear that you are directing your response directly toward them . That much is unambiguous. Whilst forest fires in the 'Republic of Ireland' are 'on topic' for the idea of 'things being on fire' in general, they are not relevant to things that have 'been on fire on Cannock Chase'. Outwith the whole 'Cannock Chase' thing, all sorts of things find themselves on fire, like, all the time. Are we supposed to be fascinated by all of them?