> I'll have a closer look at English translations of Sir Olave/Elveskud

Jamieson's and Prior's are translations of Grundtvig's 47B, the text from Syv Peder's Kæmpe Viser. Jamieson was given a copy of Kæmpe Viser by Grimur Thorkelin in Copenhagen in 1805, when he on his way to take up a tutoring post in Riga, and did his Danish ballad translations from it. I don't know Danish either, but it looks as if his translation is pretty close to the original, line by line, except that he expands the one-line Danish refrain into two lines. (He also introduces an obscure English archaism "the hend" in the first line for the Danish word "hand", which -- so I was told by a Danish professor -- is just an old spelling of the pronoun "han" = "he", so it should just be "Sir Oluf he has ridden...")

In that version, Her Oluf is out inviting guests to his wedding feast when he comes on some elves dancing. The elf king's daughter invites him to dance, offering him various gifts (buckskin boots with golden spurs, a silk shirt, a golden helmet), but he refuses and she curses him with sickness and pain. He rides home, tells his mother what has happened and dies. His mother and his bride die of grief.

Clearly a related story to our ballad, but not very close. Apart from involving an elf princess in a group of dancing elves and not a solitary fresh-water mermaid, Her Oluf is presented as a much more innocent victim than Clerk Colvill.