"Interesting credit on the song playing when you open Tom's site."

Credits are usually expressed as: Author / composer.

In Mary's version ('Oh No My Love Not I') she "extended/amended and rearranged the constituent parts (two highly amended verses from Lucy White, a verse from Peacock's Newfoundland collection and part of a verse from Mrs Overd, plus bits from the Newfoundland Sailor broadside with the sexes reversed. The rest is pure Humphreys. Cecil Sharp's tune from Lucy White, has only been ever-so-slightly fiddled with, so I have declared it as Trad."

So the author is Humphreys, the composer is Trad.

I rearranged the words and added a new last verse, and arranged a new accompaniment for solo guitar. So the arranger is Bliss.