Youth unemployment is up and GCSE grades are down. The odds are that it is the most disadvantaged young people and the most deprived parts of the county that are affected most by both.

As pupils go back to school, the debate over this year's GCSE results continues. It is the impact that GCSE grading can have on a young person’s future prospects that causes so much concern. GCSE results determine whether a young person can go on to study A-levels en route to university. They also matter to employers.

The map of GCSE attainment looks remarkably similar to the map of youth unemployment. We published research today that shows that the lower GCSE attainment is in a city, the higher youth unemployment is. GCSE results, especially Maths and English, matter to job prospects.

Official national figures with more detail on this year's results aren't due out till early next year. But if previous results and the experiences of individual schools are anything to go by, it is the most disadvantaged that are hardest hit in the apparent move to halt grade inflation. Pupils eligible for Free School Meals are far more likely to get scores around the C-D border.

Year-on-year, children from disadvantaged backgrounds are far less likely to get five good GCSEs. Social background remains the strongest predictor of educational attainment in this country; more so than many other developed countries.

Unsurprisingly, cities with higher proportions of pupils from disadvantaged backgrounds tend to have lower attainment rates overall. Over 59 per cent of pupils from all schools in the most economically successful cities achieve at least five GCSEs including Maths and English but excluding vocational  equivalents. The attainment rate drops to 47 per cent in weaker cities creating a gap of over 12 percentage points.

These pupils face multiple disadvantages. They are more likely to go to an underperforming school: 40 per cent of schools in weaker economies  are judged "inadequate" or "satisfactory"  compared to 26 per cent in economically successful cities. They are less likely to leave school with the qualifications education providers and employers require. And local employment options are likely to be more limited.

All of this serves to reinforce the socio-economic divides that have long existed across the country. 

What is also striking is that schools in many of our weaker cities are better at improving the performance of  pupils from disadvantaged backgrounds than economically strong cities. While there are fewer pupils from disadvantaged backgrounds in buoyant cities, they are less likely to achieve good GCSEs than disadvantaged pupils in struggling cities.

It is clear that policies to address educational inequalities cannot start and end with schools; there are many reasons why some pupils fall behind. But the experience of schools in some of the most deprived parts of London demonstrates that a child's background does not always pre-determine how well they do in their exams. Nearly 58 per cent of disadvantaged pupils in Tower Hamlets achieve five good GCSEs including Maths and English compared to a third nationally.

The fact that Tower Hamlets is located in one of the most economically buoyant cities in the country can't be ignored. It may affect pupil aspiration and schools may have access to a larger pool of teachers. Cities should, seek to understand what be learned from initiatives such as the London Challenge that led to marked improvements in attainment rates. One thing is clear. Without intervention to improve the education levels of our young people, the cycles of disadvantage will not be broken.

Naomi Clayton is a Senior Analyst for Centre for Cities. [2]