Expanding the number of grammar schools in England will “increase inequality” in the education system, the highly influential thinktank the Institute for Fiscal Studies (IFS) has warned.

Last week, prime minister Theresa May set out her hugely controversial plans to expand selection dramatically across the education system in a bid to improve social mobility. 

Ms May said the move to an expanded selective education system would be a shift “decisively to support ordinary working-class families”.

But the IFS has issued a warning, stating that, under a selective system, while children who pass the 11-plus tend to do better, those who fail do worse than they would have done in a comprehensive system.

The thinktank pointed to research looking into the expansion of grammar schools in Northern Ireland during the 1980s. The study showed that average attainment across the province did rise as whole, with a 10 per cent increase in pupils getting three or more A-levels.

But the expansion also led to a “decline in the performance of pupils not able to go to grammar schools”, it said.

‘Obvious disadvantages’

Researchers at the IFS also highlighted that education inequalities were wider in the country’s remaining selective local authorities, such as Kent and Buckinghamshire.

Ensuring that new grammars are socially representative would rely on introducing a “quota system”, something the government has already signalled it intends to do.

But the IFS said this approach would have “obvious disadvantages”, including “lower quality teaching, fewer resources, negative peer group effects, or unduly low expectations” in the non-selective schools.

Author of the IFS observation document Luke Sibieta said policymakers would be better served trying to understand why results in inner London have improved, rather than expanding selection in the system.

Summarising his response to the government’s proposed policies, Mr Sibieta writes: “Grammar schools therefore seem to offer an opportunity to improve and stretch the brightest pupils, but seem likely to come at the cost of increasing inequality.

“Inner London, by contrast, has been able to improve results amongst the brightest pupils and reduce inequality. This suggests that London schools probably offer more lessons on ways to improve social mobility than do grammar schools.”

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