The Vaughan Williams Memorial Library is run by EFDSS - the English Folk Dance and Song Society. However, please don't dismiss it as purely a source of English traditional song and dance materials. There's Scottish stuff too, and also valuable historical material.
Karen got very excited when she discovered just how much is there to be found. Do take a look! The catalogue is online, so it's easy enough to put in a few keywords and check out what's there.