Tunesmith – to answer your question as to whether LD "had any positive and lasting impact on the UK folk music scene" would require a lengthy article, which I don't have time to write tonight. But please give some consideration to the following points.

1) There is ample testimony that LD's early records opened up the ears and minds of a great many people – directly to various kinds of American roots music , and indirectly to the roots music of their own home countries. Without this stimulus, the folk revival would certainly have been different – and it might not have happened at all.

2) More importantly, LD persuaded a great many people that music did not have to be a commercial product, churned out for them by the entertainment industry.    Thousands of them went out and bought instruments, learned how to play them, and started making their own music in their own way. This undoubtedly had a considerable impact on the development of the folk revival in the UK.

Perhaps if LD may had been run over by a bus in 1954, the course of musical history would not have changed all that much. Maybe someone else (Alexis Korner?) would have stepped in to fill the vacancy. Possibly the Kingston Trio (or Burl Ives?)would have sold a few million more records on this side of the pond. And perhaps the worthy efforts of Lloyd, MacColl, Seeger, Kennedy and the EFDSS would still have kick-started the folk scene of the 1960s, even if skiffle had never happened.   But personally, I doubt it.

Wassail!