The difference between a song about the Battle of New Orleans and a 1970s Irish song is about 150 years - in other words, the difference between something that's now history, and something that's in living memory. When there are people alive who have suffered personally, or lost friends or family in the 20th-century Irish troubles, it's wise to be sensitive to this when choosing your song.

And yes, there was a time when you could sing rebel Irish songs even in very Protestant parts of the North of Ireland. I'm thinking of the early 1960s (I know because I lived there then), in the lull between the IRA action of the 1950s and the violence that marked the start of the more recent "Troubles". It was quite cool then to support the Republican cause and the civil rights marchers. But once the violence began in the late 60s, you had to be more careful what you sang and where. And (as implied above) it may be OK for an Irishman to sing a certain song but less so for an Englishman to do so - it's a bit like telling a joke against your own nation, I suppose, in that it's less acceptable coming from a (relative) outsider.

Marje