Its not the school's problem, they have a duty to run the best possible school, not to provide a county-wide education.
The councils should mind but they have their hands tied by the government. Its a sad fact that one of the reasons schools like Ravenstone are so popular is that they have a pretty big slug of middle class parents in them. As a result the teachers get lots of respect, the kids are clean and well fed and the PTA raises money like a banker at bonus time. In that atmosphere you can actually teach.
The "working class" schools have huge problems with dirty unfed kids, children whose parents don't support the school (teachers getting beaten up for telling off a kids are not urban myths) and roles models who are mysognistic and aggressive. Education then becomes more about crowd control than teaching.
Its an awful generalisation but if you watched the BRITS last night you have kids like Plan B and Tiny Tempah rolling up and giving "attitude" and you have the middle class bands like ColdPlay and Blur saying thank you to everyone and acting grateful. Imagine a school full of Plan B's!
This could be fixed but the only way is to allow schools in working class areas to have strict rules on exclusion and admissions. But the downside of that is you have some kids who are effectively thrown on the rubbish heap at the age of four or five because of their parents, not them. And that absolutely isn't fair.
Its tough, but shouting at renters isn't the solution