Paul D wrote:
"I'm currently looking at the Child ballads with happy endings – it seems many have never been recorded or even sung!"

I once sang 'Lamkin' - one of the nastiest of 'em all, with few morally redeeming features - at a festival ballad session. After the conclusion, "The Lamkin was hanged, high up on a tree / and the false nurse was burned, such a villain was she", a few people in the room were visibly upset, but then the silence (punctuated with stifled sobs) was broken by Jeff Warner who said, in his brashest New England tone, "Well, at least there was a happy ending!"

The point being, what do you call a 'happy ending'? Many of the ballads feature revenge as a theme, and this can lead to a satisfying conclusion despite the bloodletting along the way. Or you do mean ballads with no nastiness, and a happy ending? In which case I nominate 'Hind Horn'.

The other Paul wrote:
"My worry is always that these accompanied and in some cases "modernised" interpretations will be frowned upon by by the cognoscenti."

I don't think there's anything at all wrong with accompaniment however weird and wonderful, so long as it doesn't get in the way of the story. Listen to Tim Eriksens's 'Long A Growing' on 'Songlinks', on which he accompanies himself on a mandolin with cigarette paper interlaced with the strings to give a strange, buzzy drone, and ends the piece with throat singing. As S O' P points out, droney stuff often works well in creating an appropriate atmosphere.

My guess is that the old ballads were sung on these islands almost exclusively without accompaniment for several hundred years, and that putting guitars and things behind them dates back only as far as the 1960s. However, Ewan MacColl for instance wasn't didactic about it: the groundbreaking 'Long Harvest' collection that he and Peggy Seeger put out in 1967 used (I quote) "sparing accompaniment on 5-string banjo, guitar, Appalachian dulcimer, concertina and autoharp". Peggy has always used banjo to accompany ballads.

The only thing I really disapprove of relating to ballad singing is a lack of committment.