The release of GCSE results on Thursday will end a nervous wait for pupils. There will also be some nerves for the government, as results from the next wave of reformed GCSEs subjects are announced for the first time. Undoubtedly, there will be a debate around the need for a new, more stretching GCSE curriculum, and on the number of passes and coveted grade 9s awarded.

What is likely to be missed is any discussion of the government’s progress in closing the attainment gap between disadvantaged pupils and their better-off peers. The Education Policy Institute’s latest report delves into the data to find out where England stands when it comes to the disadvantage gap.

Reforms to qualifications and the school accountability system make it difficult to understand what is really happening, so while our findings are relatively clear in the early years and at primary (the gap is slowly closing, standing at 4.3 and 9.4 months respectively), the story at GCSE level is far more complicated.

One way is to look at what has happened to the government’s preferred measure of attainment - Attainment 8 - over time. But attempting to measure the gap by calculating Attainment 8 scores before 2016 runs into some rather large problems - with scores skewed by the particular accountability system of the time. This means that instead you end up measuring curriculum choices, rather than underlying standards.

For example, many non-GCSE qualifications, popular just a few years ago, have been removed from school performance tables altogether. Not all non-GCSE subjects have been excluded though, with some targeted by schools in a bid to boost results. The European Computer Driving License - which saw entries soar by over 2,000 per cent in 2014-15 - is a case in point.

Comparing Attainment 8 scores over time, therefore, is just not feasible.

The gap between rich and poor

For more consistency with tracking the gap, it is better to examine the average grade per GCSE subject, or the average grade in maths and English language GCSEs. The former allows for a suitably broad measure of academic attainment, while the latter allows us to measure core subjects that have been consistently undertaken by nearly all pupils.

But even when considering these two measures, trends in the disadvantage gap over recent years differ. Since 2011 the gap as measured by the average grade in GCSE English and maths has shrunk by 6 per cent to 18 months. While that’s welcome news, the pace of closure is increasingly slowing, and our estimates now predict we are over 100 years from reaching parity.

Using the average grade across all GCSE subjects, we see more welcome news, with the gap having closed by almost 11 per cent since 2011. Why the larger shift?  One driver is higher mean point scores in reformed English and maths GCSEs disproportionally boosting the 2016-17 average grade per GCSE subject for disadvantaged pupils (who take fewer GCSEs, meaning English and maths count for more in any average).  

Changes in subject entry patterns, as a result of the EBacc, also play a central role. 2016-17 appears to have been a year in which disadvantaged pupils favoured more ‘academic’ subjects - particularly those in which their grades were closer to their more affluent peers.

English literature is a prime example. The proportion of disadvantaged children studying the subject jumped by almost 17 percentage points that year, for a total increase across all pupils of 13 percentage points. Despite the relatively larger influx of disadvantaged children, the subject attainment gap just for English literature fell by 6.6 per cent. This shows that the push to boost the number of disadvantaged pupils undertaking more academic GCSEs has not resulted in them floundering; quite the opposite.

So why do we not use this optimistic outlook to estimate when the gap will close? It is because there is a limit to how much a shift in subject entry patterns can contribute to closing the attainment gap in future. Ninety-three per cent of disadvantaged pupils took English literature in 2016-17, leaving little room for further increases. Nor do all subjects have smaller attainment gaps than English language and maths. In other words, this was a one-off hit.

Ultimately, the most reliable way for policymakers to assess the extent of disadvantage in education over the long-run is to focus on the disadvantage gap in GCSE English language and maths. To continue to close this gap, real progress must be made in improving the results of disadvantaged pupils in these core subjects.

This means tackling the teacher recruitment and retention crisis, getting more experienced teachers in schools serving deprived communities, and ensuring that funding levels allow for sufficient resources to be targeted at disadvantaged children.

While the government may have abandoned talk of addressing ”burning injustices”, let’s hope that the conviction to tackle social mobility remains.

Daniel Carr is a senior researcher at the Education Policy Institute