When we talk about 'class' it seems obvious that the US and the UK aren't talking at all about the same thing.

When we in the US say something like "S/he has/showed a lot of class." we are actually admiring the person's poise in a difficult situation or perhaps a lack of vindictiveness in response to it. We really are not referring to their upbringing or how much money they have.

In the US, the upper class refers to someone who has enough money to live the way they want to or that other people would want to. The middle class also has enough money but may have to budget funds for certain things, like a desired college for their child. The lower middle class also lives well but doesn't have the expectations that people with more money have.

Lower class people- now, here it gets tricky because we are referring not to money but to a way of life or a lack of character. Nobody wants to belong to this class.

So, it seems to me that in the UK, you can be poor but upper class while in the US that is an oxymoron.

This, of course, is a gross generalization, and specific to my own perceptions only.