The pupil premium has failed to close the attainment gap between children from deprived backgrounds and their richer classmates, new research claims.

Analysis of the latest GCSE results by thinktank Demos suggests that the national attainment divide has widened slightly since last year, despite significant government investment in the pupil premium. In 2014-15, £2.5 billion was allocated to schools to support pupils from lower-income households through the premium.

Although 33.7 per cent of pupils on free school meals achieved 5 A*-Cs at GCSE including English and maths, among other pupils the figure rose to 60.7 per cent.

This means that the attainment gap now stands at 27 percentage points, an increase of 0.3 per cent from the previous year.

The new figures come after it emerged that prime minister David Cameron’s pledge to maintain current levels of per-pupil funding - albeit not rising in line with inflation - does not include the pupil premium. 

According to the Demos analysis, more than half (51.3 per cent) of local authorities saw an increase in their attainment gap last year.

Researcher Ian Wybron said: “These latest figures should be showing the positive effects of the government’s pupil premium and yet we’re still seeing a rise in the national attainment gap for a second successive year.”

The analysis suggests that schools in London are seeing some of the biggest increases in the attainment gap.

Last year schools minister David Laws said primaries in England would be handed an extra £22.5 million to help close the gap between the poorest pupils and their classmates.

Mr Wybron added: “It’s worrying that more spending doesn’t seem to be closing the gap between more and less affluent pupils. While changes to examinations will be having an impact, they can’t fully explain this failure.

But Demos’ claims were disputed by the Department for Education. “It is nonsense to say that the attainment gap is widening,” a spokesman said. “The 2014 results - when analysed with our more informative and accurate measure - show the gap has narrowed by almost 4 per cent since 2012, the year after the pupil premium was introduced.

“This is a testament to the hard work of teachers and parents across the country.”

Although the Conservatives have not announced any plans to axe the pupil premium, the party has as yet made no firm public commitment to future levels of funding.

Mary Bousted, general secretary of the ATL union, said it was important that “funding for the most disadvantaged school pupils should not be put at risk by an ideological approach to cutting public spending”.

“While we are still learning about the most effective use of the pupil premium, ATL would be dismayed to hear that the principle of supporting those who most need help is under threat,” she added.