Westminster Poorer pupils are falling further behind the middle classes at school as better off families increasingly colonise the best state secondaries, new figures suggest.

An analysis of government data by the Conservative Party shows that the achievement divide between rich and poor schools has increased by two percentage points in the space of a year.

Ministers will be disappointed with the findings. The underachievement of working class pupils has become a recurring theme of educational debate and significant resources have been directed at narrowing the attainment divide.

But although the proportion of teenagers gaining five good GCSEs continues to rise each year, the new Tory analysis suggests improvements have not been equal across all social classes.

The figures show that the proportion of teenagers achieving five good GCSEs including English and maths, in poor schools, where more than half of pupils are eligible for free school meals (FSM), decreased from 14 to 13 per cent between 2006 and 2007.

At richer schools, where less than a tenth of pupils are eligible for free school meals, the proportion increased from 57 per cent to 58 per cent.

The result is a widening of the achievement gap from 43 to 45 percentage points, suggesting that far from being a leveler, school is increasing the disparity in life chances between rich and poor pupils.

Michael Gove the Shadow Children's Secretary said that parents were being let down by schools that were effectively blocking opportunities for them.

Conservative plans to allow good new schools to open in deprived areas, with extra cash for children from more deprived homes, would reverse a growing social class gap.

“Our plans for state-funded independent schools, based on the successful Swedish model, could make a real difference to the life chances of children, particularly in the poorest areas.

“Making schools answerable to parents rather than bureaucrats has worked in other countries to improve education for everyone and it could work here too,” he said.

Mr Gove said that the existing system favoured those who were fortunate enough, or rich enough, to live in areas with good state schools.

With the looming recession adding to the scramble for top state places, particularly at grammar schools, which have seen record applications this year, the achievement gap could be set to widen.

The figures highlight the massive influence of parental background on a child’s educational success. Although an average of 65.7 per cent of teenagers across the country achieve five good GCSEs, in the worst areas fewer than a quarter of the poorest students do.

Figures from the End Child Poverty campaign show, for example, that in Nottinghamshire, where the school performance gap is among widest in the country, only 22 per cent of children on free school meals achieve five good GCSEs compared with 59 per cent of students not on free school meals.

Alan Smithers, Professor of Education at the University of Buckinghamshire, said the achievement gap shown in the figures could be partly explained by the 'grammar school' effect, as grammars tend to attract better off pupils, whose parents can afford to tutor them privately for the entrance examination.

In addition, the best teachers in the state sector tended to be attracted to the highest performing schools, with the result that pupils in disadvantaged areas could be left with the weakest teachers.

"We know that the most important factor in school performance, after the pupils, is the quality of the teachers. It's possible that the system is becoming more uneven and that some children are getting a much better start in life than others because of the teachers they encounter," he said.

But John Dunford, general secretary of the Association of School and College Leaders, questioned the figures. "I am very surprised about this because we had thought that the improvement in GCSE results had been greater in schools serving more disadvantaged areas. There has been a lot of investment in things like one to one tuition in these areas," he said.

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