Dave Re- Moonshiner.
At the time of writing MacColl was not intending to write deathless verse but rather to devise something that could be picked up quickly by anybody - that is why it became as popular as it did - it doesn't detract in any way, as far as I'm concerned from it being a classic; Mancunian or otherwise.
It was something he did all the time in those days - how about:

That lovely night, the night we met,
There where whistling bombs in the air,
No bankers dining at the Ritz
And the refugees slept in Berkley Square

I may be right, I may be wrong,
But the newspapers say it's no lie,
The rich folks children sailed away
And left all the workers kids to die.

Simple, to the point, and very, very obvious

As he developed as a singer and writer his technique became more subtle but he never abandoned the technique of using another tune unaltered - as Noreen pointed out - Champion = Limerick Rake, Tunnel Tigers = William Taylor, Che Guevara = Banks of Sweet Primroses. One of his best songs IMO was The Joy of Living, a straight lift of a Sicilian traditional tune.
I was re-wiring the lights in their home while he was writing the songs for a Festival of Fools and he used to drive us bloody mad wandering about the house whistling and humming under his breath until he had finally adapted a tune to fit what he had written, at which point he would sprint upstairs and record it.
Peggy said that he used the 'Famous Flower' tune at least a dozen times for songs he'd written; I could only ever recognise one - Shoals of Herring.
Regarding the original question - personally I find the Tams/Coope version far more offensive than any Irish version I have heard - talk about the bland leading the bland -a good, powerful campaigning song gelded as far as I'm concerned - but that's me!.
Micca:
"completely morally bankrupting"
I trust you are joking, but I fear you aren't. I presume you have the same objection to songs about old men who can't get it up any more - ageist or what? And as for all those bloody whaling songs..... oh dear, where to draw the line (whoops - was that the complete works of Shakespeare flying out of the window?).
Personally, I believe that all those god-awful hunting songs were the result of a secret policy carried out to lobotomise the rural population of England, but I would go down and fill my pint or have a pee while they are being sung rather than to prevent anybody from singing them.
Taken to its logical conclusion, we'd all end up singing 'I had a little nut-tree' (that is, if it didn't offend us republicans).
Jim Carroll