There will always (thank goodness) be exceptions that buck the trend, but I think the correlation between poverty and underachievement is real, growing, and well understood - from what I've seen on here.
What I don't understand is why it got so bad under Labour, and and why the Coalition are going to make it even worse.
I brought three kids up in a council house on an estate a mile from the notorious Moss Side (which, btw, I walked through on my own late at night on numerous occasions, and never got stabbed or shot, in spite of what the media used to say about it).
We had a decent 3-bed house with two big gardens, wide streets and lovely neighbours. Kids went to excellent local primary and comp - I really feel they had the best education and the happiest childhood they could have had, given that they were from a broken home. I supported them entirely on my own - once I got my degree.
What has changed? Well, I certainly wouldn't have been able to afford £6000 or £9000 to go to uni, for a start. Our lovely schools would probably be opting out of LEA control now, and would take one look at our address and suddenly find they were full. The streets are clogged with cars; council houses are no longer yours for life. (The number of sleepless nights I had wondering what on earth would happen to my kids if I died. The only thing that reassured me was that they wouldn't be kicked out of their home. Even that consolation is not going to be available to people in council accommodation for much longer).
In effect, I was given just enough help from the state to allow my family to survive and flourish. Now they're going to take it away, and people who make mistakes early in life, or who are just unfortunate, will never be able to raise themselves from poverty. Why are they doing it??