Here's one tentative suggestion; it doesn't sound quite like Vashti Bunyan, but you might find some of the same quality of peacefulness that you mentioned in your earlier message. I guess you can find it on amazon and hear samples?

Custer La Rue singing Appalachian ballads on her CD True Lover's Farewell. She grew up in a Southern singing family, learned ballads at home, but then studied music and these are arranged with members of the Baltimore consort playing early musicy arrangements, lute etc. Very lovely voice, but maybe more spirited and energetic than what you are looking for, with less airspace. But the CD as a whole might evoke a kind of tranquility.