Interesting article. The author also suggests:

In the twentieth century folk singers have produced musical plays with folk or folk-like songs called "ballad operas". Alan Lomax, Pete Seeger, Burl Ives, and others recorded The Martins and the Coys in 1944, and Peter Bellamy and others recorded The Transports in 1977. The first of these is in some ways connected to the "pastoral" form of the ballad opera, and the latter to the satiric Beggar's Opera type, but in all they represent yet further reinterpretations of the term