Loreena McKennitt sings it beautifully too. It's on one of her earlier albums, with very spare instrumentation I seem to recall. I even prefer her version to Mary Black's, which is saying something.

I've just listened to Sineád, and I like her delivery but unfortunately find the persistent rhythm of the accompaniment too instrusive, and it's just distracting. I wish I could hear her without it. That powerful song does not need to be "dressed up". I'm afraid I find the Unthanks' version quite underwhelming, sorry Spleen!