Would you say that self-isolation might be an appropriate measure to stop the global spread of Irish music?

The implication of the core model was to use contact tracing (to reduce the size of the core and restrict their infective contacts with the periphery): "the tests show it's definitely Cooley's, we need to know who you got it from and who you might have passed it on to..."

Most of the reels the Irish got from the Scots travelled in the years around 1800. Those that were borrowed later had more varied fates. "The Musical Priest" is quite a bit changed from Marshall's strathspey - and while Marshall changed it a bit himself, he didn't think of making it into a reel; he first published it as "Miss Watson" in B minor, then "Belhelvie House" in C minor, then "The North Bridge of Edinburgh", again in B minor. (The C minor one works great on an F alto recorder like a lot of Marshall's flat-key tunes, and that's what I play it on).

It's sometimes said that Donegal "Highlands" are a version of the strathspey, but they aren't interchangeable by a long shot. I can't recall coming across one that used an adaptation of an actual Scottish strathspey, but they're not something I've spent much time on.

Jigs also had a less predictable Irish career - Ireland had been Europe's biggest jig producer since 1600, so if they imported one, there had to be something special about it. Or they did something special with it, like the great improvement they made to the dogged and charmless "The Rock and the Wee Pickle Tow", making it into "Out on the Ocean". That was a real flash of imagination.