With so much to-do about origins & scorn for revivalist were-foxes in such a small field, perhaps it would be of interest to note that were-foxes (kitsune) are (still) rampant in Japan, where they pull exactly the sort of tricks described in "Reynardine." That name means fox, the original singers didn't use the word for no reason, & the motif of human/animal metamorphosis is one of the most widespread and ancient of superstitions. It would seem that the attachment of historical references to a typical & universal myth would obviously (& predictably) follow such a song wherever it wandered.