Conrad, I'm very much with you on the shifting purposes of these songs - it's this very ambiguity (between print and oral traditions; and between the homespun and the commercial) which I think makes music from the North East a special case. By the way, have you ever heard the rumour that Tommy Armstrong wrote a ballad for the Stanley explosion (1909, I think)? Some people are convinced he must've done this and the ballad's been lost, but I can't quite believe something as important locally would have just disappeared.
As to operatic renditions - yeah, exactly: I agree that it depends on the sensitivity of the individual singer to different musical styles -nowt inherently wrong with big voices (just think of Margaret Barry)!
BigPinkLad - Talking of big voices ... isn't Brian Johnson's version of "Byker Hill" just fantastic?
If you want to follow up on additional questions, the main one is - what is your personal definition of Northumbrian music? Where are its geographical and stylistic boundaries? Tricky one, I know - I reckon it's one of those unanswerables, but I'd love to hear as many subjective opinions on it as possible.