And isn't it written that McColl based his singing style on the Muezzin and other melismatic & decidely non-English vocal techniques, & encouraged others to listen outside the box for similarly essential inspiration?

Such inspirations notwithstanding*, in terms of ethnomusicology, I believe the cause of indigenous music & culture is best served by indigenous people - which is why the thought of a Naturalised Australian throwing away his Own Good Culture to mimic that of a country which he has no evident appreciation or understanding of a tad irksome.

*I, for example, use various non-Western musical hardware to accompany my performance of English Speaking Traditional Song but I make no attempt to play the music of the cultures this hardware comes from. Please note, this is a personal preference and not a manifesto, published or otherwise. Similarly, when I tell Norwegian folk tales, I do so in English.