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Phew, I was beginning to think I was invisible. lol
Our landlord is an ex gas fitter (no longer registered gas safe) so I think he knows what he's doing when he cleans out the fire, he just tends to hoover the dust from inside and the soot that has fallen down the chimney behind it. He does it every year before the safety check is done and we've not had a problem before, this time though the ceramic radiant seems to have burned black which is slightly worrying.
Hopefully someone will have an answer for me or I'll have to call the landlord out and I hate having to do that :-/