'History and the Morris Dance' by John Cutting - discursive and conversational but at the same time very informative, a book narrated with an enthusiast's voice seeking to disentangle the myths from the history.

And another vote for Ciaron Carson's 'Last Night's Fun' - poetic, impressionistic, and beautifully observed. Quite simply the best book I've ever read about music, LNF captures what playing the music actually feels like, what traditional music means to people, and about the social aspects of music-making.