Familiar -- but a little bit of both. It's a commonplace that English/British society is classful in a way that American society is not. That may well be true (I'm not qualified to judge), but America definitely has its own class distinctions. I would have trouble, though, putting them on a "lower, middle, upper-middle, upper"-type scale.

On the other hand, I guess the story struck me mainly as an example of someone using irony as a personality statement, which can be done without reference to class. Just today when I was at the store I was idly playing with the idea of buying a Hello Kitty iPhone cover. (I am a 38-year-old male.)

Edit: I can't think of an American analog of the garden gnome (we have them over here, but if they're as fraught as they are over the pond it's gone over my head), but when I try to think of a home-and-garden decoration that I would only display for irony (or maybe if a dear friend gave it to me), I think of a Thomas Kinkade painting.

For a historical perspective, take a look at John C. Calhoun's statements on the need for racial hierarchy precisely to avoid the rise of class divisions among white Americans.