Read Natalie Solent on school league tables:

What absolutely terrifies state schools is not that the tables will fail to measure school performance accurately but that they will succeed.

I rather think that the line of argument in the initial complaints, back in the days of raw results, was selected in the confident expectation that, for reasons of politics or technical difficulty, no one would ever work out a metric for value added. That made it safe to complain that the tests were unfair while not looking as if you were objecting to being assessed per se. Teachers rightly sensed that your average salesman or bank employee isn't going to weep over teachers having to undergo performance assessment when it is routine in his or her own job. Anyway, now it turns out that it was not a safe line of argument. Someone has bothered to work out a means of measuring value added. Oh sheesh kebabs.

Next question: how do you measure the "added value" of an education blog?