Harrison probably took the lay of Fulk fitz Warin from Leland's Collectanea - it is printed in Hearne's edition Vol. I (1770), 230-7 - rather than from the surviving manuscript, BL, MS Royal 12 c.xii. But the story of Fitz-Henrie and his elopement with Kudall forms no part of it, and must be Harrison's own addition or embellishment, taken from an unidentified source.