but for every Lord Franklin, there's a bunch of trite ditties about life on the farm (for example), with little value except in their antiquity - "Out with My Gun in the Morning", anyone?

Profundity lies not in the intention, rather the experience, which is the essence of vernacular song. In this respect I'd say OWMGITM is a good deal more profound than Lord Franklin, in the same way the simplest of finely honed pop numbers might easily outweigh the most bombastic prog anthem in terms of relevance to common-or-garden human experience and longing, despite, or even because of, the irony. In the case of OWMGITM it lies in the fact of such a pastoral idyll being printed up in the mean dark streets of Manchester's Oldham Road, the buildings of which still stand in stark testimony to the trade & history. As an idyll it's a heartfelt cry of the disposed proletariat uprooted from their heartland and crammed all anyhow into the city. Escapism in its purest, profoundest sense, as a lot of pop music is; purely & simply, and free from all pretension, presumption or proscription, be it political, poetic, or whatever...   

Question is though - Is it a Folk Song? For sure there is a very splendid broadside (See Here For So-Clear-You-Can-Almost-Smell-It Scan) and a nice old recording of Jimmy Knights singing it word-for-word with touching sincerity, having got the song from someone who (horror of horrors!) wrote it down for him. Are there any other sources and variants, I wonder? I've never seen any. Idiomatically it's a different matter, of course, it's a Folk as the nose on your face, but in terms of the prevailing usage in the classic sense on this thread (mostly MtheGM & Colonel Cairoli) I guess it ain't.