Fore warned is fore armed so to speak. It isn't by any chance fitted
to an old chimney ? If it is, then is the chimney lined with cope ?
Or does the flue just need swept ?

Lots and lots of questions and no answers yet till you get there.
Still, it can't be that bad. :-))

They seem to think the chimney was swept last year "well the one in the
other room was anyway".............it's been fitted for 17 years.