There was a recent This American Life episodes about this. Apparently the best way to raise poor black children's scores is to remove segregation, but white communities don't want it:
Depends where you are. London is deeply racially divided. There are effectively black-only schools and white-only schools. There are also schools almost completely dominated by various other ethnic groups too. The divide includes both the teachers and the students.
Yes, the US has race disparities above and beyond what the UK has. Part of this is because the US brought slaves to its own shores, whereas the UK kept them far afield and ultimately denied them citizenship.
http://www.thisamericanlife.org/radio-archives/episode/562/t...
I'm from the UK and was genuinely shocked. While there are disparities and issues over here, they're on a different scale compared to the US.