I have Phil Tanner's version of Barbara Allen (The Gower Nightingale, Veteran VT145CD) - the most exquisite and comprehensive CD version ever! I had a hand in this CD, and John Howson deserves plaudits for publishing the CD.
In case you don't know Phil: He was born in Llangennith, Gower, in 1862 and died in 1950. He was a tenor who soaked up songs like a sponge - in the King's Head, Renoldston, Phil started singing and didn't stop to closing time, a total of 88 songs in all. He knew the Celtic "mouth music" and sang The Gower Reel for villagers.
I must look up the words of Barbara Allen, but I'm spending Christmas at Olly's (AND it's my birthday session at the Boar's Head in Tyle Garw, just across the level crossing, 8pm, Monday) so I'll have the words on Monday.