Nearly 20 years ago, as then education secretary David Blunkett’s special adviser, I helped to introduce a programme for gifted and talented pupils in urban secondaries. The initiative focused the efforts of many comprehensives on new ways of tailoring provision for more-able students. The programme sadly lost its way in the later years of the Labour government, though its legacy lives on in some schools and academies.

More recently, Sir Michael Wilshaw, as chief schools inspector, reported annually on how schools were catering for their more-able students. Ofsted inspectors now ask about the progress of high-attainers. But we are still grappling with many of the issues we faced nearly two decades ago - and we need to ask, are we doing enough through accountability to encourage schools to support high-attainers?

This summer, parents and businesses will learn that GCSE results are no longer as easy as ABC. Grading results on a 9-to-1 scale is the last in a series of steps that could have a profound effect on accountability in secondary schools. But whether the changes also help stretch able students as much as they support those with poorer test scores aged 11 remains an open question. There is a good case for addressing their needs more directly.

The debate around how to ensure that less-advantaged pupils of high ability fulfil their potential is not uncontroversial. Some say a focus on top test scorers at 11 - those in the top 10 to 20 per cent - means missing out on others with the potential to be just as successful. Others want the focus to be much more on low-attainers - those who don’t get the expected standards in English and maths - and argue that the £2.5 billion pupil premium should be entirely directed at them.

But this cannot be about pitching groups of students against each other. The Sutton Trust’s Missing Talent research showed that over a third of disadvantaged boys and a quarter of disadvantaged girls, who were in the top 10 per cent of pupils at age 11, were outside the top 25 per cent in their GCSEs. Meeting their needs was an argument for Progress 8 - the new GCSE school-success measure - in that every grade is now credited, so getting a student from a 2 to a 3 is rewarded as much as getting from a 3 to a 4 or a 6 to a 7 in the new grading scale. The system has its teething problems, but its intentions have been good. However, recent arguments about whether a 4 or a 5 is equivalent to a C grade, and the continued importance of floor targets, suggest that border lines haven’t disappeared.

Wasted talent

I was never as convinced of the evils of the C-D border line as some were. For employers or sixth-form admissions, a C proved to be far more valuable than a D. Focusing there did more than improve a school’s league-table scores. But the old system failed to accredit schools properly for getting students As rather than Bs, limiting opportunities for higher-achieving students to access Russell Group universities including Oxbridge.

As our Chain Effects 2017 report highlighted, there is still much to do. Sponsored academies are good at improving results for low-attaining disadvantaged pupils, but are weaker with their high-attainers. Given that these academies often serve the poorest communities, this disparity should be of concern.

All this matters to social mobility. The Office for Fair Access reported recently that disadvantaged young people remain far less likely to get to our best universities - and from there to access good professional and well-paid jobs - than those from better-off backgrounds.

The gap is still as much as 10:1 on some measures, though it has been wider. That isn’t just bad for those individuals, it is bad for society and bad for our economy to waste so much talent.

Before the election, the government saw an increase in grammar schools as the answer. But while grammars often do a good job for the disadvantaged students on their rolls, our research has shown that far too few such pupils are admitted in the first place.

Indeed, there is a gradient linked to income in grammar school admissions, not just a gap. Moreover, the evidence is that highly able pupils in the best-performing comprehensives do just as well.

Now that new grammar schools are on the policy back burner, policymakers must not forget the needs of able students from less-advantaged backgrounds. In fact, there is a real opportunity here for comprehensives to live up to their mission to cater for the needs of students of all abilities.

Three important steps could help: the first is to encourage fairer admissions to the most successful comprehensives - the top 500, based on GCSE results; these schools only take half the proportion of poorer pupils that live in their catchment.

Randomly allocating half the places in successful urban comprehensives - backed by outreach and travel support - could open such schools up to those who can’t afford the house-price premium attached to these schools.

The second is to excite and engage more able students with a curriculum with greater enrichment, as well as access to more demanding lessons and lectures - in partnership both with other schools and universities. The Sutton Trust has moved from working only with sixth formers to supporting able 12- to 15-year-olds through its Sutton Scholars programme. And the government should support schools and universities in trialling what is most effective for highly able students.

Finally, we need to look again at how schools report their results, and how their success is judged by Ofsted and regional schools commissioners. We shouldn’t just report the overall Progress 8 and Attainment 8 scores, but we should specifically report on the results and progress for high-attaining students.

We could then see exactly how the best comprehensives perform - encouraging others to emulate them - and how they compare with grammars on a fair measure. Ofsted and regional schools commissioners would look at these results alongside the main scores. But more importantly, this could do a lot to improve social mobility, too.

Conor Ryan is director of research at the Sutton Trust. He tweets @conorfryan