Two hundred years ago did the music of the pleasure gardens, broadsheets, hymns and Percy's reliques have 'a lot to do with each other'?

Pleasure garden songs were printed on broadsides, so an obvious connection there. 'Reliques' was based on written sources and available only to a small section of society; setting aside Child's enthusiasm, it has only marginal relevance to folk song. Hymns were generally sung from hymn books.

I'm not sure of your point here.