Recently, I read Malcolm Gladwell’s book Outliers again. When I skim-read it a few years ago, I enjoyed it, but I failed to digest some of its significance for education.

In the chapter “The Matthew effect”, Gladwell demonstrates that in many fields, particularly sporting ones, a person’s birth month can have substantial consequences. His wide range of examples show that someone born in the first few months after an age cut-off will have a huge advantage when it comes to playing top-level sport in later life. This is because of the developmental benefits that six to 10 months can give a young person over their peers.

A child who turns 5 soon after the beginning of a school year will be nearly 20 per cent older by the time a child born at the end of it reaches their fifth birthday. At the age of 10, that is still a 10 per cent advantage, and by 15 it’s just under 7 per cent.

As a physical education teacher, I saw this repeatedly in my career. And it is not just a matter of physical advantage. In 2009, the National Federation for Educational Research reviewed 18 studies published between 2000 and 2008 and carried out in Australia, Chile, the UK and the US, together with information from a further 13 countries and states. All the studies found statistically significant effects resulting from students’ relative ages.

Generally, students who were younger did less well in attainment tests. Research conducted in the US and Chile found that relatively younger children more often had to repeat a school year. In the UK and the US, they were more frequently identified as having special educational needs.

Two British studies found a statistically significant increase in incidences of psychopathology and referral to psychiatric support services among relatively younger children.

Based on the above and my own experience, here are my predictions for any state secondary school:

- Where maths and English language classes are set by academic attainment, the top group will prove to be older than the lowest group.

- Those students who are excluded from school will be younger than the average for their year group.

- The youngest 10 per cent of students in any year group will be in a lower socio-economic group than the oldest 10 per cent.

This last point is a bit of a hunch, but I suspect that parents in higher socio-economic groups will hold their child back if they feel they are likely to be disadvantaged by going to school too young.

If I am right, we may need to consider preventing younger children from lower socio-economic backgrounds (particularly boys) from starting primary school too early. This would give them the 20 per cent head start that some of their peers enjoy by making them the oldest in the year - and it would perhaps balance out other handicaps associated with poverty.

Don Ledingham is director of innovation leadership at personal development consultancy Drummond International.