I must admit that I'm fascinated by this song, but it has too many variants to mention. I think there are over 125 versions in Swedish, and I remember Pete Coe singing 'The Wind and the Rain', which is where I first connected with it. Having said this, Mike Raven published 'Bonnie Bonnie Banks of the Virgio' in a guitar tutor, many years ago - and I think this may be another variant. I seem to remember him claim that, 'This song may have viking origins'. But of course, that idea is not completely uncommon.

This thread is interesting, as it references Brewster. I bet a native Icelandic speaker would have little trouble in tracking down a local version.