I don't see any reason for regarding it as ironic. Two or three shirts doesn't sound particularly "doing well" to us, but it is clearly an improvement to the collier in the song. Not every folksong is a tirade against social injustice, so surely this is a modern misunderstanding. It may be meant ironically by modern singers, but is that a legitimate part of the folk process?

It is certainly Walker Shore as far as I am concerned, being a native north-easterner and having known it before hearing the Carthy/Swarbrick version. Without having a full list at my fingertips, I believe we can rule out any other pit in the area, and the "walk ashore" is surely a joke?