For what it's worth, Morton Castle is in Nithsdale (Dumfries and Galloway), and was built in the late 14th(?) century on the site of an earlier fortified dwelling. In the later 15th century a branch of the Douglas Family (later Earls of Morton) acquired it. It has been uninhabited since the early 18th century, and is now a ruin. Loch Morton, by which it stands, is apparently a man-made loch. One of the tourist websites mentions a phantom coach and horses, but I haven't found much else; and tourist sites will always add a ghost if they can.

The history of the name Edgar has the following to say; no source seems to be identified for the text, which at least reads as if taken from a 19th century source:

"There are place-names in its vicinity which show that the possessor of the barony had the right of pit and gallows. At some little distance on the hill east of the castle stood an aged thorn, which was uprooted many years ago by a hurricane of wind, but which was known as Judgment Thorn, and the tradition of the country still points out the spot where it grew; while close to the farm-steading of Morton Mains are Gallows Flat and Hangingshaw, where doom of judgment was carried into execution."

I have corrected a number of textual errors, likely the result of pasting in an OCR scan without checking it. Of course, that may all be completely irrelevant. A great deal of our spare time in those days was spent in murdering each other on the slightest pretext.

Nathan Rose of Harvard has done some work on the ballad, and presented a paper entitled "A literary history of 'Child Owlet' (Child 291)" at the 26th International Ballad Conference (Swansea, 1996); I don't remember if it has been published.

I see that John Faulkner's recording also appears on a CD titled 20 Famous Irish Ballads. I should imagine that he is rather embarrassed about that.

A search for instances of "Chylde" Owlet returned more than enough, though with no useful information; mostly crediting the lyric to Peggy Seeger(!) Most or all examples of the text available on the web have clearly been copied directly from the DT, and are of no additional use.