Nice to see this old thread pop up again, with its examples of how people are convinced that THEIR local version is the original!

Malcolm Douglas quotes above from Sam Henry:
It is a most interesting point in topography that the hero of the song was drowned in the lake (no longer on the map) which gives its name to the Barony of Loughinshollin (the Lough of the Island of the O'Lynns). The O'Lynns (originally O'Flynns -the F, being aspirated, is not sounded) were a powerful sept who, in the 6th. century and from A.D.1121 onwards, occupied a territory comprising the modern baronies of Lower Antrim, Lower Toome, Lower Glenarm and Kilconway, on the east side of the River Bann. The lough was probably an expansion of the river not far north of Lough Beg."

A week or two ago, I was flicking through some old maps in a Dublin bookshop and happened to spot "Loughinsholinn" along the Bann in one of them!

Regards