Thanks for reviving this thread. I've downloaded the MIDI linked by Malcolm Douglas. I think it will make a nice addition to my flute and dulcimer tunes.
I fear that whoever originall wrote "The following TĂ ladh or croon is said to have been sung by a kind-hearted fairy who, calling at a house, found a child lying in its cradle, its mother having apparently deserted it," was far too trusting and did not know much about fairies.
Why were the fairies called "The Good People"? They were called the Good People because they were bad. They were feared because they loved to cause trouble.
Telling a baby that its mother has deserted it when in fact the mother has merely gone off on an errand is typical of fairy malice. Actually, the hard-pressed mother has probably left the room briefly to punch down the bread dough or to get a four-year-old child out of a tree.