The book is "Tree of Strings: a history of the harp in Scotland" by Keith Sanger and Alison Kinnaird, 1992. According to this, Rory Dall Morison (one "r") was born in 1656 and died in 1713 or 1714. He came from the Isle of Lewis. The two Rory's are often confused, simply as "Rory Dall", and indeed often thought of as being the same person. O'Kane visited Scotland a lot too, adding to the confusion. However, as we can see, Morison was in fact born after O'Kane had died.

The Dictionary of Ulster Biography credits O'Kane with "Tabhair" and possibly, "The Londonderry Air".

If the Scots must try to steal an Irish tune, then with this one, they have certainly gone for one of the absolutest finest. As the Clancys used to say when introducing "Will Ye Go Lassie Go" - "if you must steal a song, steal the best"!