Well, these songs of terminal regret were 10 a penny in the 17th to 19th century. Apparently it was as a result of the inadvisability of having a girlfriend with an insatiable shopping habit. They come under the banner of Adieu, Adieu, Willow Day, The Flash Lad and various towns, Newry included.

The version I like best comes from the singing of Suffolk singer Jumbo Brightwell.
And I always assumed Valentine O'Hara to be just another of those Irish mondegreens (like Shores Of Erin for Shoals Of Herring).

Maybe Jim could enlighten.