This is the tune I have been thinking of, but never thought to look at my (large collection of) Pogues' CD's. LOL This tune is also on the playing list for my musical friends, and sadly for my mental health, I no longer play music with them but that's another story.
A note on The Session page for the tune says that The Pogues credited the tune to Spider Stacy
I looked at my CD's by a couple of other artists e.g. Tim O'Brien, a CD by Butch Baldassari, Robin Bullock & John Reichman, etc but nothing seemed to fit and then I started hearing Repeal of the Licensing Laws in my head.
It may not be exactly the same tune as Angelita but it is definitely in the same style and also, I am not sure of the actual history of the RotLL tune either.
Also, I keep forgetting to say that on the Newtown live video page there are a couple of comments from 4 years ago and someone said they have the lyrics of the Angelita song. Whether the email is still valid now is another question.