"Let Her Go" (revisited)
He says that the line "Let her go, let her go" is "not native to the song 'St. James Infirmary.' Rather, it is a graft, from an old song which may be of Irish origin. It's variously known as 'Go and Leave Me If You Wish To,' 'Dear Companion,' or 'Fond Affection,' and it's a song of lost love (lost as in an abandoned lover, not lost to death). It's really a family of songs, just as 'St. James' Hospital/Infirmary' is, with somewhat fluid boundaries. It's also a line that floats into a few other songs, including 'Sweet Heaven.'" He points me to the "Traditional Ballad Index," associated with the folklore department of California State University, Fresno, where there is an entry on "Dear Companion."
I remain as confident as I can be, without having any access to Costello himself, that it's "St. James Infirmary" he was quoting in "Ascension Day." But I am extremely interested in the general thread that Mr. Stamler has pointed me toward here. While I hadn't really thought about it, the "Let her go" stuff is not in "The Unfortunate Rake," so it must have been added in at some point before "St. James Infirmary" emerged. I don't have direct familiarity with any of the songs cited in the entry that Mr. Stamler pointed me to, but now I have a new wish list of tunes to track down and listen to.
I'll keep you posted, of course.
Thanks, Mr. Stamler...