Like the festival's inspiration, Hamish Henderson, Warner's parents went out into the field across the Atlantic to record singers who had songs passed down through their families and having inherited the fruits of this research, Warner presents a rich tapestry of American life, many facets of which have all but disappeared.
His is a scholarly presentation, with dates and locations included in his introductions as a matter of course, yet there's nothing academic about his performance. This is a man who knows his stuff and shares his enthusiasm for his topic as easily and naturally as he does the choruses that have helped workers get through the days, weeks and in some cases, winters of toil.
It's a travelogue as well as entertainment, with stopovers in Cornwall as well as Carolina and speculation as to whether songs originated over here and emigrated there or vice versa. Accompanying himself with concertina, guitar and the wonderful, undemonstrative momentum of his frailing banjo style, Warner sings with genuine warmth and great authority and adds a terrific sense of fun as he sings Jay Ungar's agreeably daft Chicken song and introduces his dancing friend, a small wooden figure whose dance steps beat an intricate tattoo on a plank of wood.
Witty recitations, a peanut vendor's sales pitch and even Polly Wolly Doodle, complete with virtuoso bones accompaniment, all contributed to a night of superbly rendered folk music-cum-social history.