i'm disgustingly middle class according to those definitions. however, that's not to say that my circuimstances haven't changed throughout my life. if we're going by the marxist definition of class as anyone who works for a wage and has no source of other income, then i am working class. it feels wrong saying that though, because i'm not, i know i'm not.
i'm not ashamed of comin from the p/b. i'm highly unlikely to enjoy the same standards of living my parents did (and my parents both came from upper working class/lower middle class backgrounds anyway). and even if i did i've seen enough of life to know what side i'm on. there is an element sometimes on urban where people are thought to be doomed to be middle class "no matter how poor they get later on" like jon says. however i think it's important to know that education etc and the background of your parents, how much money you had growing up, do give you certain (although frequently slight) advantages. it's important to realise that, but i do think that class also sometimes changes throughout life. it's just that in this day age social mobility is more likely than anything else to be downwards unless you are in a very fortunate position.
for example, i'm probably going to have to work until i drop. my parents arent in that position. (yet).
and you also have to look at the life of the average p/b business owner. when my parents worked for example they had no life, they worked at the weekends and in the evenings until past 9pm/ frequently to past midnight. constantly. i hardly ever got to see them. their entire lives were taken up with work. i'm not saying that materially i had to struggle or anything like that, but remember that a lot of the material wealth comes at the cost of never being able to do anything else except work. and now, even more so - for smaller and smaller rewards due to inflation etc.
i'm in no way saying that it was really hard or anything like that. and i also think you have to understand the advantages in terms of cultural capital that this can give you - even if you are cash poor there are still frequently advantages in terms of jobs and an education if you are "middle class" such as accent, etc.
i'm not trying to get you to feel sorry for me or anything. it's a really complicated issue. and there's no doubt that i've had it easier than others - and it's a good idea to look at these discussions rationally rather than assuming tht it's an attack on you. you can't help your background. as a wise man said , it's where you're going - not where you're coming from. and right now the way i see it even relatively lucky people like me are going in the same direction. unfortunately there are some people who can't see it yet and they are perhaps the ones i feel sorriest for.