Hey, perhaps Tim Finnegan represents the Irish rebel rebublican voice, Biddy O'Brien is the sympathetic irish citizen, and Miss McGee represents the less politically inclined irish voice. To quote Dominic Behan about the song: "Take away the possesive quality of the noun by simply removing the apostrophe and you have a great war cry to all the sons of Finn McCool, 'Finnegans, Wake!'".
Or maybe it's just that it's a good song to encourage audience participation. I would like to hear some examples of things shouted out in some other parts of the world. For example, after "his head felt heavy which made him shake" crowds here in California shake their bodies and heads. After they wrap him up in clean white, "No sheet!" is shouted. After his widow calls for lunch, everybody shouts for lunch. When Biddy stars to cry, the crowd wails and then when she says, "such a lovely corpse did you ever see?" some people will shout, "biggest stiff she's seen in weeks." In the next verse, after "it was woman to woman, and man to man," folks shout out, "sounds like a party at my place." And finally, "when a bucket of whiskey flew at him," the singer is pummelled with napkins from the more raucous crowds. I'd like to know if this is regional, and if so, what else do they shout out. Maybe I just need to hang out at better pubs.