The findings - described as “political dynamite” by a headteachers’ leader - show that schools expect to cut 1.2 per cent of posts this year, and 2. 2 per cent next. One-fifth of schools anticipate having to axe posts this year and one-third in 1995-96.

Even if the cuts are only half as great as predicted, pupil:teacher ratios will rise to a level not seen since the mid-1970s.

Professor Alan Smithers, director of Manchester University’s Centre for Education and Employment Research, who carried out the survey, said he had been surprised to discover the complicated and inequitable way in which funding reached schools. “The idiosyncracies mean some schools think the whole crisis has been got up by the media, because they have done well financially.”

He found it odd that heads had to juggle nationally determined costs, such as the teachers’ pay rise, against local variations of spending per child, leaving some with little room to manoeuvre. And it was “absurd” that schools had to get rid of experienced over-50s in favour of cheap, newly-graduated staff.

He was convinced of the need to look again at the financial differentiation between primary, secondary and post-16 pupils and for some sort of national funding system for the amount of money following each child, probably with extra elements of core funding per school and a safety net for individual needs. Local authorities were a good means of administering this.

David Hart, general secretary of the National Association of Head Teachers, said the figures confirmed teachers’ worst fears: “There is no doubt we are facing the biggest funding crisis in many a long year, maybe since time immemorial and I think Professor Smithers’ figures are political dynamite.

“I think the Government will find it very difficult politically to shrug off these statistics which demonstrate that they are in grave danger of going into the general election in 1997 knowing that class sizes are going to be higher than they were when they took over in 1979.”

He thought the debate was moving in the direction of some form of national funding, but warned that there would have to be consensus and it was fraught with difficulty. “For instance, if the Treasury took control they would have a choice between funding best practice, medium practice or worst practice. There is a tendency among Treasury mandarins to opt for worst practice, I suspect. ”

The Manchester survey was carried out in January and February with a representative 2 per cent of primary schools and 10 per cent of secondaries. Job losses of 5,060 this year and 8,964 next are predicted.

Pupil-teacher ratios also seem likely to continue their rise after a long period of falling. Although this is due in part to rising pupil numbers, Professor Smithers thinks much of the recent trend “is likely to be due to deliberate action on the part of the schools. Even if we halve the expected cuts to take account of new appointments and undue pessimism. . . the PTR is set to rise steeply by recent standards. The estimates suggest we could be back to the levels of the mid-Seventies by 1996 with a primary PTR of almost 24 and a secondary PTR of over 17.”

Another trend beginning to surface appears to be a difference in the PTR between GM and LEA secondary schools - 16.0 compared to 16.3.