Ideological Bias
"I do not doubt that fee paying schools are academically better than average, and I have already remarked that I hope to send my daughter to a fee paying school. But none of that means that all the outcomes of fee paying schools are the result of the school."This may be unwelcome news to the parents who send them there at such expense, then.
"Children who go to fee paying schools are sent by parents who are particularly concerned about education, so they are hardly a random sample of children. Why is that so hard for the Examiner to grasp?"Children who go to fee-paying schools also happen to be sent by parents who are particularly well-off. Do we really want to abandon the meritocratic ideals of this Republic in favour of a plutocracy, which is what school vouchers, etc. are designed to nudge us towards?
Update 23/11/05: Dick O'Brien also touches on this subject.