When I read Martin's comment that I quoted above where he writes:-

He also realised that some singers were capable of creating songs from scratch – to record a local event, for example.

I couldn't help thinking of Jim's long list from his post on 04 Oct 17 - 08:03 PM. I don't recognise any of these songs from their titles but the content they suggest - elections, fairs, drownings etc. seem to put them in the category that Martin was describing; and well worthy of a song collector's attention.

Yes, Steve, I will contribute to the thread that you have started, but first I have somehow to give an impression of this fascinating, wide-reaching book in a 400 word review.