Jim Carroll's observations about the English language folk song tradition being a narrative one is interesting. But like all generalisations it is dangerous if put in the hands of the uncritical. A well-thought out and descriptive bit of analysis like"most English folk song is narrative" can so easily turn into "all English folk song is narrative" and then to "all folksong is narrative" and then to "your song is not narrative so it is not a folksong" and then to "your song is not narrative so we dont want to hear it, in fact it's not a song at all".
I too have been involved in a lot of folk music collecting recently, mostly non English language actually: and I would be very wary of any generalisations about folksong, whether in terms of form or function. Because I am well aware that generalisations can become very prescriptive in the wrong hands