This is some more from Rowland Parker’s The Men of Dunwich, about the town that thrived as a ship building port before the sea ate it.
Dunwich eventually finds its place on the map… in or about the year 630 A.D., when it was called Dommoc. Or something similar. Bede was the first person to write the name, about 130 years later. He presumably wrote what he heard, then someone – several people.. copied what he wrote. They rang the changes on Donmoc, Dumoc, Domoc, Domnoc, Donuuoc. … King Alfred embellished it to Domnoc-ceaster (the camp, or fortress of Dunwich); which might have been speculation on his part, or he could have known something definite about that possible Roman fort which we do not know.In the end the writers settled in the main for Dunwyc or Donewic, a good Saxon-sounding name, but one still leaving scope for speculation as to what it meant.