Ah, I see. On some of these supposedly Irish music-hall pieces, one can do no better than recall the judgment of Donal O'Sullivan, "Songs of the Irish", c. 1960; he wrote that they seemed to have been made "for mental defectives". Mind you, Irish people still love French's "Mountains of Mourne" (for instance), with its simple-minded protagonist thinking that navvies are "digging for gold in the street", or that a policeman directing traffic must be Head of the Force, since of course he "stopped the whole street wid wan wave of his hand". Anyway, "thread drift".