ALMOST one in four primary school pupils in a North-East town are still taught in classes of more than 30, figures show.
And the proportion in oversized classes is above one in ten in nearly every other authority in the North-East and North Yorkshire.
The Liberal Democrats described the figures as "shocking" and accused the Government of failing children who would receive a better education in smaller groups.
But the department for education (DfES) insisted its pledge to cut class sizes had only ever applied to infant schools, an area where it had made "great strides".
The situation in Darlington - where 23.9 per cent of primary pupils are in classes of more than 30 - makes it the tenth worst-hit education authority, says the DfES.
Other blackspots are North Yorkshire (16.8 per cent), Durham (16.3 per cent), Redcar and Cleveland (13.2 per cent) and Stockton (13.2 per cent).
The highest numbers of pupils affected are in North Yorkshire (7,203), Durham (6,206), Stockton (2,125) and Sunderland (2,096).
Two authorities - Middlesbrough and North Yorkshire - also have a small number of pupils being taught in classes of over 40, the survey, carried out in January, revealed.
Edward Davey, Lib-Dem education spokesman who uncovered the figures, said: "These shocking figures show just how badly the Government has failed to get the basics right,
"Instead, it is concentrating resources on providing better facilities and on offering extra tuition in arts, music, sport and foreign languages.
A DFES spokesman accepted there had been a small increase in the number of primary pupils in classes of more than 30, to a total of 584,170 across England.
But he added: " Much of this will be temporary and the funding is there to keep classes at a historically low level."
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