Mark Gregory,do you believe that what Bert said was true? THIS:
Indeed, as far as song
is concerned, that is the present stage of folklore development:
nowadays there is far greater use of the folk-song repertory and of
folkloric forms of creation in our industrial towns than in the
countryside."

Seems to me to be pretty broad but not so broad as to become meaningless and to take into account an understanding of the importance of industrial folk song or folk music in an industrialised era.
Doubts about some of Berts scholarship exist ,some of his own songs have been passed off by him as traditional .