Malcolm, I agree that it's best to ask first and to try to access the actual libraries, but finding good info related to folk music is often a bit more difficult for those of us who live outside of London. For example, up here in Newcastle we've lost our main reference library for a couple of years while they renovate the building. Lovely as the new site will probably be, that means a lot of stuff in storage and inaccessible for quite a bit of time. That's why I thank heaven for inter-library loans!