A bleak picture of cuts across the board in secondary schools has been painted for John Major by headteachers.
Papers sent to the Prime Minister by the Secondary Heads Association talk of cuts in budgets, teaching staff and in spending on books and equipment.
SHA has warned him that unless money is found to make up for past cuts and provision made for inflation and population growth in next year's settlement, the education service will deteriorate.
With Pounds 500 million lost from education budgets this year and ministers now battling for their department's funding, SHA has told Mr Major that the 1996 teachers' pay award must be met in full.
John Sutton, the association's general secretary, said: "It is not just the cuts of the past year which concern us. The level of service has been steadily eroded over several years and there are few opportunities left for so-called efficiency savings.
"Further cuts can only mean larger classes, fewer teachers, book shortages and even, in the worst affected schools, shorter hours for pupils. The time has come to stop the rot."
At least 12,000 teaching posts are estimated to have been lost in schools during the past three years, according to the National Employers Organisations for School Teachers. And more are predicted to go. Governors have predicted that 4,500 will have been cut by the end of this year bringing the total to around 16,500 in three years.
The figures, published last week, provided the first clear statistical snapshot of the pressure local authorities are under because of the Government's refusal to fully fund the teachers' pay award.
Headteachers, through SHA, have told Mr Major of the impact on their individual schools.
Hartford high school, for example, an 11 to 16 comprehensive in Northwich, Cheshire is facing its fifth successive year of cuts. Staffing levels have dropped from 61.4 to 58.6, the maintenance budget was cut to less than Pounds 25,000 annually several years ago and the school has just Pounds 3,000 in the bank.
Peter Llewellyn, Hartford's head, said his school "will continue to function in 199596, but is likely to go into receivership next year".
Smithills School in Bolton has made cuts across the board, and maintenance has suffered. Mike Kehoe, the head, said: "We are being reactive rather than pro-active.
"Clearly this has health and safety implications, as well as resulting in an environment that may not be as supportive of the school's ethos as we would wish."
At Plant Hill high in Manchester, whose budget fell by Pounds 15,744 this year, some areas have not been painted for 16 years and outdoor facilities which need Pounds 25,000 have been neglected for six years.
"Our Office for Standards in Education report requires improvement in examination results and attendance, but financial help is not forthcoming, " said Alan Schofield, Plant Hill's headteacher.
"A hard-working staff is becoming demoralised by the constant financial restrictions. This is the first year since local management that we will not be able to prepare a balanced budget."