Have you ever had a bird fall down your lounge chimney?

Even though supposedly it has something over the chimney, a few years ago something definitely went in there. We could hear what sounded liked flapping and scratching for a couple of days and then it stopped. We can not access the chimney to find out. Many months later, a load of flies appeared on my bedroom window on the inside. I think it must've died in there and the flies got in and laid eggs. The eggs must've hatched and they all made their way through a little hole in the bedroom wall that the tv wire goes through. Horrible it was.