Their findings revealed that the average effect of abolishing league tables is substantial, a fall of almost two GCSE grades per pupil per year. This decline in performance was found to be important for the lowest performing 75% of schools, but not for the top quarter of schools.

Publishing school league tables was therefore shown to both raise average school performance and reduce educational inequalities.

Co-author and CMPO director Professor Simon Burgess said: “School accountability policies such as league tables seem to be a cost-effective way of raising school performance, particularly for students in disadvantaged schools and neighbourhoods.”

The research exploits the ‘natural experiment’ created by the abolition of secondary school league tables in Wales in 2001, and compares educational outcomes in England and Wales before and after the policy change, enabling an analysis that isolates the impact of removing league tables from two otherwise near-identical education systems.

This affects all schools except the top 25% performing schools. And the impact is strongest among schools with the most students eligible for free school meals: the poorest 25% of Welsh schools, for example, show a fall of three GCSE grades per pupil per year.