The number of state school children taught illegally in classes of more than 30 has doubled over the past two years and the figure is likely to soar next year as the twin effects of a government pledge to allow all four-year-olds into school in the September term after their birthday and a rise in the age cohort conflict with pressure for cuts in public spending.
Figures published yesterday showed that more than 10,000 five- to seven-year-olds are now taught in oversized classrooms – the highest figure since the Government introduced in 2002 a legal ban on children of those ages being taught in classes of more than 30.
One of Labour's five key pledges that carried the party into office in 1997 was its declaration that it would make classes of more than 30 infants illegal.
There are now 310 illegal infant school classes of more than 30 pupils, compared to just 130 two years ago. Last year the figure was 200.
Overall, including schools which have sought permission to defy the legislation – because pupils have arrived in mid-term or appeals against a refusal to grant a place have been successful – 930 classes of five- to seven-year-olds now have more than 30 pupils, compared with 730 two years ago.
"These huge classes make it difficult for teachers to give our youngest children the individual attention they need when they start school," said David Laws, the Liberal Democrats' schools spokesman. "With so many children in a single class, it can be difficult to maintain order and teach effectively.
"The situation could be even worse next year given the shortage of school places across the country, particularly in London. We know that smaller infant classes make a real difference. We need to be cutting class sizes to private school levels of 15."
Christine Blower, the general secretary of the National Union of Teachers, said: "The Government's pledge to reduce class sizes appears to be unravelling at the edges."
Academics say the the rise in infants class sizes is set to continue. Professor Alan Smithers, from the Centre for Education and Employment at Buckingham University, said: "It looks as though the trend is worsening. The earliest years of education are the best chance of intervening to make a real difference to children's lives."
Mick Brookes, the general secretary of the National Association of Head Teachers, said: "It's a funding problem. With 30 children of a particular age group you have one teacher; if you have 31 you should have two."
The Government has backed a recommendation from its inquiry into the primary school curriculum that all children be guaranteed the right to start school in the September term after their fourth birthday, to address summer-born children faring worse in tests and exams throughout their schooling.
Yesterday's statistics from the Department for Children, Schools and Families showed that the main reasons for giving approval to infant classes of more than 30 was successful appeals by parents over admissions (53.2 per cent of cases) and children arriving mid-term (21.6 per cent). In addition, there has been a bulge in the birth rate with 1,396,830 children in infant classes – compared with 1,367,860 a year ago.
The figures also showed a reduction in class sizes for seven- to 11-year-olds from an average of 27 last year to 26.8. In secondary schools, there was also a reduction from 20.9 to 20.6. Among five- to seven-year-olds, the figure rose from an average of 25.7 to 26.2.
The Schools minister Jim Knight said: "Infant class sizes were a national disgrace in 1997 – and it was a scandal that almost a third of children were in oversized classes. We now have strong legal measures to ensure that almost all infant classes are below 30. The less than 1 per cent that are unlawfully large must take immediate steps to comply.
"All of the unlawfully large sized classes were brought within acceptable limits and I expect prompt action to be taken again to ensure compliance."
The Tories schools spokesman Nick Gibb said: "The rise in unlawfully large class sizes underlines concern that there won't be enough primary provision to cover the likely number of children needing a place in September."