Lyn and Harpgirl
Thanks for responding. This song has haunted me for years. My recollection is that the origin of the song was unknown, but from the unarchaic language it would either be reworked or composed within the last couple of centuries. The book mentioned that there was a Porlock Sound which had historical records of being raided by Danes. So the song may refer to early events, or it may be a later version of an earlier song. I don't know of any other songs that refer to events that early (800-900s). The tune has unusual intervals, and doesn't sound to me as though it comes from the normal run of ballad melodies. It seems either from another tradition, or composed to sound different. I will try to think of a way of writing it down for you in text.
It's great to be able to communicate with someone about this. My cat was sympathetic, but unable to help.