This is not directly relevant to the debate we are having here, though it does raise many related questions. In particular, notice that nowhere is it even suggested that the difference in development across social class between children at the age of three might be partly genetic/innate. The assumption made by the paper, and apparently by the researchers, is that native wit and talent is distributed fairly evenly across the social classes.
The fact that such differences in development might be even partly down to genetic differences is, for many, simply unthinkable. Certainly unsayable. (personally, I don't think they are genetic, despite Potentilla's earlier comment. but find it interesting the way this possibility is simply airbrushed out of the picture in The Guardian).
Georges, just to remind you: I would be equally happy with all schools private, and vouchers with no top ups. If you don't rate state provision on principle, fine (though it strikes me that for many, if not for you, "public bad, private good" is an article of faith, not a well-supported hypothesis).
In the next post I will answer George's request that I come up with a concrete alternative proposal to the current system. It'll be back-of-an-envelope stuff, but I'll give it my best shot.