Unfilled teaching posts have risen by 23% in a year

Schools are in the grip of their worst staffing crisis for years, with of a 23 per cent rise in the number of unfilled teaching jobs. There are 2,510 vacancies across the country, latest figures from the Department for Children, Schools and Families show.

The shortfall is being blamed largely on a shortage of maths and science specialists, but there is also the "demographic timebomb" of older teachers leaving the profession faster than they can be replaced. Just over half of all headteachers are expected to retire within four years. At the same time, the number of trainee teachers has fallen.

The number of vacancies in nursery and primary schools has risen by nearly 32 per cent since this time last year, from 210 to 870. In secondary schools, the figure is up by 21.5 per cent, from 1,210 to 1,470. Special schools are trying to fill 170 posts. The situation is worst in London, where 1.1 per cent of teaching posts are vacant, compared with the national average of 0.7 per cent.

John Dunford, general secretary of the Association of School and College Leaders, urged the Government to improve recruitment, saying: "Schools are finding it particularly difficult to recruit maths and physical science teachers. The situation is not as bad as four or five years ago, but staff recruitment is still a major issue for schools – particularly those in challenging areas."

Primary education faces the worst shortages, with 1 per cent of all deputy and assistant headteacher posts empty – up from 0.7 per cent in 2007.

Mick Brookes, the leader of the National Association of Head Teachers, said the heavy workload in primary schools, coupled with Government targets, made teachers feel they were "under fire". "The baby-boom generation is getting to retirement age," he said. "Some work-related stress has fallen on primary schools, in particular where [staff do not have] the spare capacity to absorb additional duties. Primary heads are retiring early – at an average age of 58. This is only making the situation worse."

The Government insisted the increase in unfilled posts had only raised the vacancy rate from 0.6 per cent to 0.7 per cent. "The overall rise in teacher vacancies to 2,510 in 2008 is equal to one-tenth of a percentage point rise of all teachers in the system," said a spokeswoman for the Department for Schools, Children and Families. "We have incentives in place, such as training bursaries and 'golden hellos'. These have steadily increased the stock of teachers."

However, a recent report by the Policy Exchange think-tank said there were 10 per cent fewer applicants for teacher training this year than last summer, and 40 per cent of places on teaching courses were unfilled.