Attending a grammar school significantly increases the chance of disadvantaged pupils getting into highly-selective universities like Oxbridge, new research has found.

Today’s report, published by the Higher Education Policy Institute (HEPI), calls for the government’s selective school expansion fund to be extended to allow grammar school branch sites in disadvantaged areas, where this is supported by the relevant local authority.

It says that 39 per cent of pupils in areas with selective school systems progress from state schools to highly-selective universities, compared to just 23 per cent in comprehensive areas.

HEPI director Nick Hillman said the debate on grammar schools had become “ludicrously one-sided” with researchers condemning them for inhibiting social mobility.

He said: “Compared to other countries, we have a hyper-selective university system. Given so many people benefit from attending a grammar school, it seems what works for universities may also sometimes work for schools.”

Findings in the report, The Impact of Selective Secondary Education on Progression to Higher Education, include that:

• a state school pupil with a BAME background (black and minority ethnic) is more than five times as likely to progress to Oxbridge if they live in a selective area rather than a non-selective area;

• England’s 163 grammar schools send more BAME students to Cambridge than all 1,849 state-funded non-selective schools combined (i.e. those with sixth forms);

• a state school pupil from the most disadvantaged quintile is more than twice as likely to progress to Oxbridge if they live in a selective area than a non-selective area.

Previous research has shown there is no evidence grammar schools help disadvantaged pupils and that grammar schools in England endanger social cohesion for no clear improvement in overall results.

But HEPI says that part of the reason its conclusions “are so radically different” is that it does not look only at children from the very poorest families - those entitled to free school meals - and then compare them to the other 85 per cent of families, but looks at all families of below median income.

Report author Iain Mansfield, who is a former principal official at the DfE, said the government should now “accelerate” its expansion plans for grammar schools.

He said: “Opponents of grammar schools portray them as just for the rich, but 45 per cent of their pupils come from below median income households. So that simply isn’t true.

“A narrow focus on eligibility for free school meals has ignored many other measures of disadvantage, including ethnicity, parental education and broader income disparities.”

But Dr Nuala Burgess, of anti-selection campaign group Comprehensive Future, said it was “odd” to use below median income families as a proxy for disadvantage because they would include many lower middle class, well-educated families, such as teachers “who are hardly disadvantaged in educational terms”.

She also said it was “disingenuous” to compare university entry from “selective” authorities when grammar schools import vast numbers of high-attaining pupils from non-selective areas.

She said: “Trafford grammar schools import nearly 30 per cent of pupils from outside the authority, while in Southend it is over 50 per cent. This is bound to skew university entry figures simply because higher proportions of the highest attaining pupils are educated in selective areas.”

She added: “Some BAME groups who attend grammar schools do achieve very good results. Nonetheless, alternative research shows white British working class pupils in selective areas are underperforming.

“The best way to improve results for all pupils, regardless of social background and academic ‘ability’ is in high quality, well-funded, comprehensive schools.”

Comprehensive Future is today running a critique of the report on its website.

A Department for Education spokesperson said: “Selective schools are some of the highest performing schools in the country and an important part of our diverse education system.

“Almost all of them are rated good or outstanding, and they are popular with parents. That is why we continue to support their expansion, through the Selective School Expansion Fund, where they meet the high bar we have set for working to increase the admission of pupils from disadvantaged backgrounds.”