It looks as if there must be some orphan pages floating around but the main site seems to be OK. http://www.mustrad.org.uk/ works fine for me. That page doesn't have links at the bottom but pages linked in the left hand column (except MT Sampler as Mr Red has pointed out) do and they seem to work as far as I have tested them. The page that CJB found doesn't show up in the Sitemap. Nor does the MT Sampler page.

It looks as if it may need some tidying up but but I think it's a long way from needing an Urgent - Rescue Mission.