Yes, an interesting ambiguity. The query could mean "I am looking for English songs, but it doesn't matter if they are Irish Scottish or Manx, that would be just as nice". Or does it mean "I am looking for what I have been told are called "Celtic Songs" so they can be Scottish, Irish or Manx. But not, heaven forbid, English". Personally, I would have a look at Cornish and Welsh songs too and, yes, even English ones as well.