Kingston has the country’s 10th-largest gap in GCSE performance for poorer pupils, Department for Education figures have revealed.
The proportion of pupils eligible for free school meals scoring at least five A* to C grades last year was 38 per cent.
But three-quarters of pupils not eligible for the hand-outs hit that benchmark.
The only London borough with a wider achievement gap is neighbouring Sutton.
Liberal Democrat Councillor David Ryder-Mills, lead member for schools, said: “In a way we are a victim of our own success.
“Our free school meals students actually achieve far better than most.
“It is just that our other students succeed even better than that.
“Clearly there is constantly work to be done.”
The full effect of the pupil premium, introduced by the coalition Government, has yet to be seen because children taking their GCSEs now have not benefited from it for very long, Coun Ryder-Mills said.
The premium is extra cash given to schools for every student who claims free school meals.
Conservative opposition lead member for schools, Councillor David Cunningham, said the pupil premium was not “the whole story”.
He said: “What he [Coun Ryder-Mills] says is not incorrect. But he is not grasping the nettle. It is not just a question of putting more money into it. It is a more complicated subject than that.”
Kingston Labour chairman Laurie South said: “I think what it shows is the schools are good if you are reasonably well off or well off, but if you are disadvantaged financially in any way, you are going to get a pretty rough deal in Kingston.”
The news follows the publication of GCSE statistics showing how many pupils in the borough’s schools achieved the five A* to C grade benchmark last year.
The figure ranged from 13 per cent at Canbury School in Kingston Hill to 100 per cent at Kingston Grammar School.
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