Solve a little chimney mystery for me?

[TerrysNo2]

We've lived in our Victorian cottage for almost 6 years. It is lovely and has a fireplace in every room but we only use one. On Friday I came home and one of the fireplaces upstairs (not working one) has lots of black bits and dust on the floor underneath it. It has a piece of black metal blocking it up but it doesn't totally seal it so the bits are coming down from the side but why? This is the first time it's happened and I hoovered it up but there is more coming down every day.

Any ideas why??

Thanks

You have/had birds nesting in it. Wait till autumn, get a sweep in, and get the chimney capped.

Birds and/or nests

so the birds aren't a problem now?

apart from the fact I have to lug the hoover up the stairs every day

So long as you're not hearing the fluttering of a trapped bird, it's not a problem. But it's worth capping unused chimneys, I don't use my bedroom fire and have birds falling down it every sodding spring. (Rented house) I asked my sweep to stick something on it, he suggested chicken wire (it would work, and the fire could still be lit) and I agreed. Sadly, he put the chickenwire on the livingroom chimney, which is in almost daily use and not popular with nesting corvids. Gah.

We used to get stuff come down if there was a hail storm or birds. We had the chimneys swept and clay cowls put on them. Only have a problem with horizontal hail now (freaky British weather!)