Pamela, I found this very interesting. People sometimes ask me why I (usually!) find no difficulty in remembering long ballads and, though I've always replied that songs that tell stories are the easiest to recall, I'm now wondering whether it's the state of Zen-like calm produced by the slow breathing and heart rate that's helping. Of course we're often told to douse down our onstage nerves by taking a few deep breaths beforehand.

I was pleased that you addressed the question of the subject matter of ballads, and how narratives of betrayal and violence might be expected to negate the physical effect of relaxation. Might it be a factor that even the bloodiest ballads often end in resolution, even though that might be violent in itself?

I also anticipated the question about other kinds of singing, posed by the choir member. I was already thinking about things like chanting at football matches, or singing traditional carols in local pubs, in both of which the singing is rapid, rhythmical and sometimes almost frenzied. Presumably in that case the feelings of satisfaction would be produced by the well-researched effects on the production of endorphins, rather than the vagus nerve?

If you're right, then unaccompanied ballad singing would represent a special case, where it's precisely the slowness of delivery that produces the beneficial effect. If you listen to some traditional ballad singers, they are far slower than any revival singer, which makes me wonder whether the cultures that produced them were well aware, consciously or subconsciously, of that.