Free schools may be opening their doors in some of the most disadvantaged areas but they are not reaching the poorest pupils, according to a new report from the Institute of Education, London.

The study shows that  overall, free schools tend to be set up in needier areas - the proportion of children entitled to free school meals (FSM) is slightly higher in the areas around free schools than the rest of England.

Some 22 per cent of secondary pupils in the neighbourhoods around free schools are entitled to FSM, compared to 17 per cent in the rest of England. At primary level those figures fall to 18 and 16 per cent respectively.

However, the report also finds that the free schools are not necessarily attracting these needy pupils. Just 17.5 per cent of pupils in free secondary schools are eligible for FSM, dropping to 13.5 per cent in primary free schools.

That means that overall, free secondary school pupils are actually close to the average for secondary schools, and children attending free primary schools are very slightly better off.

But there is evidence that prior achievement differs between standard and free primary schools. Pupils at free primary schools have much higher Foundation Stage Profile mean scores than children elsewhere in that area and indeed in England as a whole.

The researchers say that free schools will need to be assessed on their value added outcomes instead of academic results in future, especially at primary level, since the intakes of free primary schools mean their pupils are already further ahead.

“It appears that, so far, the places in Reception at free primary schools are being filled by children who are somewhat less disadvantaged and more advanced in their development than the average,” says Francis Green, professor of labour economics and skills development at the Institute and leader of the study.

“This outcome may be disappointing for the government, which had hopes that its free schools policy would be a vehicle for delivering social justice.”