"he life histories of every singer they came across"
Sorry - missed a bit.
Nobody here has mentioned "life histories' other than you - I am referring to an attempt to find out what the songs meant to the singers and their communities.
We do know that many of Hammond and Gardiner's singers were discovered in unions (workhouses) - an important point, I believe.
"a proud laddie from hell"
Im sure you know the origin of the nickname - if not, look up "Ladies From Hell".
Did you know that Brendan Behan once wrote of the Scots warpipes that "the only thing to be said in their favour is that they don't smell"?
Jim Carroll