I'm an American living in England, and those are some beautiful british names :) The only one that strikes me as 'too british' is
Nigel, maybe
Winston as well as it does conjur butler images for me ;)
Imogen is a common welsh name, but I never thought of it as such, and my son has a welsh/celtic first name -
Owen - and my American family loves it.
From your list, my favorite is
Edwin, it's one of my top 5 boy names :)