"British Jews, unlike their American counterparts, have anglicized their names and their customs."
The author evidentally has not met any assimilated, southern Jews in the United States, whose families go back to Colonial days on this continent.
Are there many left? As a kid, I read a book called Mr. Benjamin's Sword, about Judah P. Benjamin, and it inspired me to go looking up the history of Jews in the US. Turned out that a large percentage, from what I gathered even the majority (until maybe the late 19th or early 20th century) were in the South.
If you could tell me a bit more, I'd be grateful.