If this helps, Mick - I heard Colum sing it on more than one occasion, and the chorus is exactly as in DT but there are also three or four distinct verses, which are sung to the exact same tune and sort of develop the basic premise. Like yourself, I looked on Colum's website but since (a) he hasn't recorded it and (b) it's not one of his own compositions, it doesn't appear on there. The tune though - ah now there's a thing - it surely isn't Auld Lang Syne, it's more like a polka, one that's probably been used for any number of Irish folksong-derived or even music-hall-derived Oirish. Colum even "stage-lilts" the final line of the chorus!
Try emailing Colum then? Or does Bonnie lie over the ocean too?