Whereas I have long regarded myself as an instant expert on every subject under the Sun. Just thinking about the line about the last rays of sun &c., had I heard that in any Irish song, I'd have assumed the "B---" word was the name of a river (or even a hill/mountain) in the labourer's own townland or at least locality. However, the man who made the song has already got listeners thinking of Birmingham from the start of this final verse, so I'm pretty confident with the suggestion. Hope someone from Birmingham taps on this thread-title. Good Luck.