Hm, I guess it is not a straight forward way to define a map like this that work for every county. But take Yorkshire for example. York is after Jore, or Jorvik, which means Horse, or horsebay. But before that it had other names, and the founding name by the romans was Eboracum, celtic borrowed phrase for yew tree place. But as I understand it, it is not really etymologially connected "yew tree" and "york". Or?