Grammar schools: what the evidence says

Few topics in education can light the litmus paper in quite the same way as grammar schools. And so it has proved with the explosion of debate that has followed from the prime minister’s recent announcement that the government would like to see new selective state schools established for the first time in a generation. 

Emotion rather than evidence has fuelled the discussion. There has been a lot of heat, but very little light.

So what does the evidence actually tell us?