"4) He is critical of English performers who do non-English material as it is a wasted opportunity to perform "good English traditional folk songs". However a substantial portion of his repertoire is hymns from "Hymns Ancient and Modern" most of which are relatively recent compositions - surely this is a wasted opportunity to perform good English traditional folk hymns?"

Indeed, The English Hymnal, edited by Vaughan Williams, was a reaction against Hymns Ancient and Modern. It was thought that a new hymnal was needed which was more egalitarian in its approach to singing, and VW deliberately utilised folk tunes throughout.

If someone wanted to play music from the traditional repertoire, they'd use The English Hymnal every time.