The BBC has the story here of a Queen's University Belfast student who has taken the university to court. The student had received a "2:2" degree classification (otherwise known as a "second class, lower division" degree). He is alleged to claim that he would have secured a 2:1 degree classification (thus, ensuring better job prospects) had he received better supervision. The case is ongoing.
Whatever the result of this case, my suspicion is that such cases may become more frequent. Whether or not this prediction comes true may come down to how this case is decided.