Throwing open their doors will have benefits for the system as a whole, says Chief Exec James Turner as he unpicks today’s new research comparing the social selectivity of top performing state schools in Great Britain.

The schools system in England is highly segregated on social class and income lines. Seven percent of children attend independent schools (with average fees of £15,000 a year), which disproportionately feed our top universities and professions. A further five percent attend grammar schools, which again are superhighways to the elite, but which also take in relatively few low income students. And even for the majority of children in comprehensive schools, the situation is far from equitable. House prices, catchment areas, faith criteria and morally dubious admissions practices all conspire to disadvantage poorer families in the scramble for the most coveted places.

The Sutton Trust has been shedding light on this issue for some time, from our first analysis of the makeup of the top comprehensives relative to their local neighbourhoods in 2005, to this week’s work by NFER on social selection in Scotland and Wales.  Across all these studies, a similar pattern has been found: that the highest performing non-selective state schools take in relatively few children eligible for free school meals, compared to national averages. In some cases this is simply because they are sited in affluent areas – or the catchment areas are drawn such that they encompass the better-off streets. In others, the schools are actually based in areas with higher levels of disadvantage, but their admissions practices (most often faith based) mean that it is the wealthier who end up walking through the school gates.

But are these schools top performing because of the very fact they are socially exclusive? If they had more mixed intakes would they simply not be on our list in the first place?

There is of course a strong and established link between poverty and performance – a link we are keen to break, but one which means a poor student in England is almost half as likely to get five good GCSEs than their more affluent peers. So the intake of these schools is certainly a factor in their high performance – but we do not believe it is the only driver. High quality teaching and learning, and advantages in terms of teacher recruitment and retention are also at play. Analysis by our sister charity, the Education Endowment Foundation, supports this view: it showed that schools with similar intakes can perform very differently – and that there are outstanding schools which buck the trend of disadvantage compared to their peers.  The more low income students who can benefit from these trail-blazing schools, the better.

But there is another, even more important reason to focus on the intakes of the top comprehensives. And that is by opening up these highly-ranked schools to a fair share of poorer pupils, we are taking an important step in making the school systems in all three countries more balanced overall. We know that disadvantaged pupils tend do better in schools with more mixed intakes.   So having schools of extreme affluence cheek by jowl with schools of extreme poverty does nothing for overall standards – even before we consider the impact on aspirations, attitudes and social cohesion.  At the Sutton Trust we have advocated the increased use of admissions ballots, priority places for disadvantaged students and reforms to faith criteria as a way of achieving a better spread of social backgrounds across all our schools. This is especially important in urban areas where school choice often entails oversubscribed schools picking pupils, rather than families getting the best educational fit for their children.

So we think that who goes to which schools is important in the social mobility equation. It does of course need to go hand-in-hand with the biggest priority: raising standards in all schools, but especially those with the most disadvantaged intakes. It is right that this should be the main focus of the governments in England, Scotland and Wales, which all now have Pupil Premium-style funding devoted specifically to supporting the poorest students. And with the help of tools like the Sutton Trust / EEF Toolkit, there is more information available than ever before on where best to spend these marginal pounds.

But that is a big mountain to climb. The Education Policy Institute believe it will take another 50 years, on current forecasts, for the attainment gap to close in England. In the meantime we need to break the strangle-hold of the wealthiest on the highest performing schools, whether they be community or faith-based comprehensives, private schools or grammars. Throwing open their doors will have benefits for the system as a whole.