Ian Carmichael singing the theme tune (What in the world would I do, Jeeves? was wonderful, and presumably has been saved for posterity.
Americans? Lord Emsworth's nephews and neices are always marrying Americans. The lovely Sue Brown is part American, IIRC. The Luck of the Bodkins is set on a transatlantic liner with American characters. Dyspeptic American business men with bossy wives are as frequent as aunts. And that's only from memory.