I am not sure if it is the same James Nell, but a few years ago I had been in contact with a James Nell who referenced a book by Raymond Boyd Nell of Pennsylvania. I have a copy of this book and I believe there is one in the National Archives. I couldn't find a connection to my family as these Nell's were relative new comers to the US (I believe early 1800's). My ancestor, Jesse Nell was born in Dumfries Virginia 1755. I have also done my DNA analysis. Happy to share info if you like.