In fact, Pentangle didn't record the song until about 1994; I was probably thinking of the Jansch recording (late '60s/ early '70s).  Shirley Collins also recorded the version found by Lloyd, on the influential album she made in 1964 with Davy Graham, Folk Roots, New Routes, which is probably where Jansch and Renbourne got it if they didn't get it directly from Lloyd.  Even Lloyd didn't record it till 1966.  He seems to have modified the text quite a bit over time, and I strongly suspect that it was he who introduced "his teeth did brightly shine"; Shirley Collins got "his eyes so bright did shine" from him a few years previously.  On that, and on one unsubstantiated remark by an Irish poet and song collector, rests the whole "this is a werewolf/ werefox/ vampire story" canard...

Malcolm