Following yesterday's posting, I was gratified to see that Kirsty Williams responded promptly and characteristically with a firm rejection on behalf of Wales and liberal democracy of Mrs May's divisive secondary education policy.
In her statement, Kirsty quotes the Sutton Trust who found that "found that less than 3% of grammar school pupils were on free school lunches, compared with 20% across the country". This is evidence, against the Conservatives' "dogma and doctrine, rather than looking at what actually works for our young people."
There is even better evidence that comprehensive secondary education has not held back bright children from low-income homes. In 2011, Swift and Boliver published the results of a rigorous study showing just that. The report was even given prominence by the Daily Mail at the time. Dr Adam Swift admitted in an interview with Lawrie Taylor on Radio 4's "Thinking Allowed" (thanks to the Open University's collaboration with the BBC the episode is still available to download) that he did expect to see some beneficial effect of grammar schools. In the event, there was a slight advantage to some people from poor backgrounds who had managed to get into grammar schools but only in the lower half of the earnings table.
It is misleading to compare grammar schools in isolation with comprehensive schools. Secondary education needs to be looked at as a whole. When you do that, you do not find the disadvantages to the comprehensive system claimed by the Conservatives. Indeed, other research shows that the best predictor for upward mobility is not the school system but parental background and ambition.