I've been wondering, but haven't found anything to suggest that so far. According to what I have read, and that's off the internet, it was first collected by Roy MacKenzie who did his collecting here on the mainland. I don't know of any Gaelic songs which use the tune, of the Derry Down. The only other song I've encountered using that specific tune is the Mauling Live Oak as I mentioned earlier, which is a Maine Lumbering Shanty. It's hard to say. Still, Halifax wasn't settled by the Scottish people exclusively.
I am wondering how they traced it that far back to the 1750s. Is there a song with the Derry Down chorus which dates back that far?