"Thanks Jim, here I am again!"
Welcome aboard!
All this has set me off to thinking that tackling songs in unfamiliar accents - or taking the easy way out by parodying them in 'Oirish' or 'Mock-Jimmy', can come about because of an underestimation of your audience - "what does it matter how I do it, what do they know, so I might as well do a 'Clancy Brothers Soundalike'", or in my case on occasion "they won't follow, or be interested in what I'm singing about so why do it?" and revert to the tried and tested 'Desert Island Discs' fall-backs.
Not directly related to accents, but MacColl used to tell a story against himself of when he started singing long ballads in public back in the 'Ballads and Blues' days
One of the earliest of these was 'Gil Morrice' which he decided was too big a bite for new audiences, so he broke it into two halves, one in the first half and one after the interval.
"One night a young feller who had recently become a regular; A great big trouncer who used to deliver beer locally, hands like crane-grabs"; (Ewan elevated exaggeration into an art-form), "came up and rather aggressively asked me "Why do you sing that ******* song in two bits; it's like waiting for the other bleedin' shoe to drop?""
He used the story to illustrate his belief that any audience was on your side from day one, and if you realise that fact and respect it "you can get them to follow you anywhere - over the White Cliffs even"
He believed that "Any problems in communicating a song was far more likely to be through a lack of confidence on the part of the singer rather than an inability to follow by an audience, any audience"         
Jim Carroll