I've been looking recently at 'Through Bushes and Briars', which is often sung these days with the first verse repeated (the song itself is partly a Vaughan Williams confection anyway). I think it rounds off quite nicely a song that doesn't have a strong narrative, although there's no evidence that the small number of traditional singers who knew the song used to repeat the verse. On the other hand, such a device would only be appropriate to a performance context, so a singer faced by a toff with a notebook probably wouldn't have bothered anyway - and who's to say the collector have noted it, even if they had?

And I know it's off topic, but I really can't let Jim get away with "Folk song has never been about joining in."

East Anglian pub sings such as Blaxhall and Eels' Foot were full of joining in, to the extent that singers would deliberately repeat the second half of each verse to serve as a chorus. Cyril Poacher's 'Green Broom' is a classic example (I've always been tickled by such an old magical ballad being turned into a singalong number), but only one of many. He sang the repeats in the pub, but not when recorded at home. Not quite the same as repeating the first verse, but still a participatory invitation quite unneccessary to the narrative.