Just off the top of my head:
Harriet
Winston
Rupert
Fiona
Alfie (God, I hate this name!)
Neville
Nigel
Archibald
Basil
Reginald (though I also consider this a black American name)
Annabelle
Imogen
Beryl
Most of these are either very oudtated (how many Nevilles under the age of 60 could you find, even in Britain?) And most have never been popular in the US anyway, like Rupert, which will probably never catch on. So it wold be a bit odd to see most of these in the US, although Annabelle and Fiona have gained some use with certain types of people.