My son was very young at the time, five or six I think, and not really interested in his dad's music. However, I played him a song from a Waterson's CD that became a favorite. We often sang in honour of the foxhounds named in it: "Dido, Bendigo, ..."
I think the term for their music is "polyphonic singing," but I've no background in music to describe the mixture of harmonies and dissonance that makes my eyes open and the hair on my neck stand up. I just know that I love it.
Here is one song I learned well from them. It is a lament for the passing of the lifestyle of the "travelling men," the gypsies, the tinkers.