Thanks, Gibb! None of the biographical databases like VIAF or LoC have dates for Erskine… Literally nothing about him except authorship of Twenty Years. I hadn’t found his obit.

Erskine claims he learned his letters at sea; I assume his “correction” of “Highland Laddie” is hypercorrectness… which would make sense if he hadn’t actually heard the songs in use. But this is good information, and I’ll have to reconsider my hypothesis…