its a bit like blaming Bix Beiderbecke for not playing funk, Blind Lemon Jefferson for not plugging in a strat....

Kathleen Ferrier had her place in history, as we all do, and she acquitted herself with distinction. Well done kid! You did what you could with where you found yourself.

middle class people singing folksongs in an authentic folk voice is a relatively recent thing. and it has its fans, and more than a few detractors.