Vast improvements in London’s GCSE results among poor pupils are down to the capital’s primary schools and not its secondaries, a report has suggested.

Disadvantaged pupils in London have made dramatic improvements in the past decade, which has led to them achieving significantly better exam results than those elsewhere in England.

The so-called “London effect” has mainly been attributed to higher standards in secondary schools, thanks, in part, to the London Challenge. But according to a study by the Institute of Fiscal Studies, the root of the increased attainment lies in primary schools.

Luke Sibieta, programme director at the IFS and one of the authors of the report, said the work being done in the capital’s primary schools was “crucial”.

“The higher level and improved performance of disadvantaged pupils in secondary schools in London over the past decade is a remarkable success story,” Mr Sibieta said.

“Our work suggests that specific policies focused on London secondary schools, such as the London Challenge, may not be the main reason for this improvement. Instead, it appears to derive largely from improved performance in primary schools. Success at primary schools is clearly crucial.”

The research comes ahead of another major report on the secrets behind London’s success, which is due to be released by CfBT and the Centre for London later this week. 

The London Challenge, introduced by Labour in 2003, was a programme aimed at improving collaboration between schools across the city, using experts to work within the schools to raise standards and boost GCSE results.

The policy is still championed by Labour’s education spokesman, Tristram Hunt, but Mr Sibieta said the role of the London Challenge, while not insignificant, had been “overstated”.

Instead, the success story behind London’s performance was due to a broad mix of students and improvements in primary schools.

According to the report, results at Key Stage 2 were significantly better in London, as well as in Manchester and Birmingham, than the rest of the UK.

The report states that there was a large improvement in English SATs scores for disadvantaged pupils in London between 1999 and 2003, which was likely to be “a key reason why GCSE results in London subsequently improved between 2004 and 2008”.

“What exactly was behind those improvements in primary schools is difficult to tell,” Mr Sibieta added.

“They did coincide with the rolling out of the national literacy and numeracy hours, but that was nationwide, so it is likely further study will be needed in this area.”