Racism is bad.
Police-State overreactions to reasonable requests are worse.
There is no version of this story that merits the involvement of the police. If she made racist comments the school can punish her. Ever heard of detention? Suspension? A stern talking to?
Can ANYONE, especially a Brit, defend police involvement here? Racist remarks are heinous, but should NEVER be a crime. If someone wants to call me Kikey Mc should-have-died-in-Auschwitz or whatever, let them. They're only exposing themselves as bigots. And there are legitimate reasons not to want to work with someone who can't communicate with you. There are also legitimate reasons to be forced to do so by your teacher. There is no reason for police involvement whatsoever.