unfortunately, the type of wiring already in place is Pyro (MICC) so I
don't think I'm going to be able to pull new wire through, more's the
pity!

seems like options are running out:
- chase out and redecorate ceiling and walls
- have odd and ugly conduit on surface
- miracle product to save the day...

pyro is supposed to be resilient with problems usually being the end
connections. I had the light checked by an electrician though and that
was the verdict.