We have no direct proof that during the 18th century the antiquarian editors were translating directly from the Scandinavian, but by about 1800 Jamieson certainly was. Most of these ballads are no older than the 16th/17th century, some even later. Of those that have equivalents out of Britain those that match up with Scandinavian ballads are much more common than from other parts of Europe. In order to make a British version one only needed the bare bones of the story. Some of them could have been translated more than once, Tvo Seostre (Child 10) for instance. What little evidence we have points towards direct translation by relatively sophisticated hands. Of course in the 19th century the likes of Borrow, Prior and Grey were translating and publishing Scandinavian ballads. If they were doing it in the 19th, why not the 18th?

In my own neck of the woods there was frequent dialogue between Denmark and the locals (As a fishing port we have long had a Danish church) but I think direct translation by ballad editors is far more likely. A lot of this is just my opinion, but I challenge anyone to try and disprove it.