Very nice ebonite (or is it slate) backboard, but what does it actually do? the only thing I have ever seen that was anything like that was the servants call panel in a stately home which had little flags on it to tell them which room was calling.
It's an old hospital (asylum), St Cadocs in Caerleon, South Wales.
Lovely old building and grounds but unfortunately the NHS are struggling to keep on top of the repairs with some of the building in need of serious work
I did a quick search for images and it looks like it is very popular with 'urban explorers'