A spot of confusion to be cleared up here.

"Martin Carthy Book" can be taken to mean two things:

-- a book authored by someone else, concerning
Martin Carthy's life and career, and its significance to
the revival of traditional music in England.

-- a book on the subject of a specific category of traditional songs, and what the songs illustrate about their time and place,
co-authored by two authorities:
one an authority on the judicial system and
the other, Martin Carthy, an authority on traditional music.

So this thread is now going in two directions at once,
as these are two very different books.