I was thinking of the "Island Field" in Limerick rather than the one in Canada.

On Kilkenny/Bohenny: Stephen Suffet also does that, and gets the same knee-jerk reaction from audiences who don't really understand the song. It's nothing new; as I mentioned in a past discussion here, Kilkenny was substituted in a Liverpool broadside edition printed around 1820. See thread How many versions of Geordie, which includes a short list of substitutions.

That particular Foggy Dew is a 20th century song set to an older tune. I thought everybody knew that by now (it's been discussed here often enough, and the lyric posted again and again), but a recent thread on tunes and songs of the American War of Independence period shows that they don't.