"But a major determinant now of which version gets learnt and performed by new singers is not any of its inherent traits but who recorded it, e.g. Joan Baez, Martin Carthy, Nic Jones ..."

As witness the popularity in the folk revival of ballads like 'The Selkie', 'Willie's Lady' and 'Annachie Gordon', all of which (whilst fine ballads) were very rare in tradition. It's all too easy to assume that balladeers of 200 years ago sang mostly about fairies, demons or incest, on the basis of what's been popular in folk clubs over the years.

When I reviewed the 'New Penguin Book of English Folk Songs' - which selected for popularity in oral collections, rather than appeal to modern singers - I was struck by the small proportion of modal tunes and gothic ballads, relative to the 'folk scene' repertoire of the last 60 years.

Seems that the tastes of a mostly well-educated and urban community in the late 20th century were different from the rural working class of 100 years before. Who'd have guessed it?