Al you're about right...
I love the perfect diction of Barbara Dickson , Maddy Prior and their beautiful voices. I hope we can all understand Tim Hart , Christy Moore Andy Irvine, Jez Lowe and countless others , but it never occurred to me to consider whether they were posh or not. Jeremy Taylor taught at a public school (Possibly Eton) but Posh ? - I'm not sure.
Yes they sing in understandable English , - but Posh ?
Kathleen Ferrier was a truly wonderful singer - not posh , but exposing Folksong in a the only way which was agreeable in period she was living.
The questioner is quiet right, in that, when a posh voice sings "Weel may the Keel row" "Blaydon races" or some such I find it a bit off-putting - I d much prefer them to be sang in natural Geordie voice
but people with posh voices, are tying their best to sing OUR songs so
I suppose my answer to the thread has got to be "Yes they can" but you may need to give them an awful lot of leeway .
Posh voices in ordinary Church services ( especially at Christmas on radio or TV ) has a similar effect on me as I suspect, does the posh people singing Folksong ....on the questioner