English schools may face an inspection only once a decade under a radical shake-up of the system to be consulted on next month.
Chief inspector Mike Tomlinson plans a package of measures intended to reduce the stress of inspections, cut bureaucracy and recognise a wider range of school achievements.
Mr Tomlinson also wants the Government to reward all improvement by scrapping the five A*to C GCSE benchmark. Instead, he suggests adopting the average point score measure used by the Office for Standards in Education.
His announcement, at a National Association of Head Teachers conference in Dudley, came as Tony Blair admitted he was in urgent discussions with OFSTED about how to reduce the administrative burden of inspections.
Mr Tomlinson said the inspection overhaul might require a change in the law and signalled that a Bill authorising the changes could be one of the first to go before Parliament in the autumn - if Labour wins a second term.
He said schools' success would be better judged by using value-added measures rather than comparisons using the proportion of deprived pupils, who are eligible for free meals.
David Hart, NAHT general secretary, welcomed the proposals. He said: "This is a vision of an inspection system which is far removed from the one which schools have had to endure.
"It recognises that bureaucracy of inspections is not just about paperwork. It is also about the fear and stress caused by the perception of inspection."
Mr Tomlinson hopes to reduce teachers' fears by giving schools about to be visited by OFSTED a copy of the pre-inspection paperwork. This sets out what inspectors' intend to check during the visit based on data supplied by the school.
Future inspections should also consider factors affecting performance such as pupil turnover, staffing problems, the number of supply and newly-qualified teachers, particularly where the inspection occurs early in the year, he said.
He said: "It is not an excuse but it seemsto me that these are vital contextual factors that people reading the report need to know to make sense of what they are reading."
Inspectors had already been alerted to the problems of high pupil mobility and told not to criticise school managers for spending time dealing with such an unavoidable problem, Mr Tomlinson said.
Some inner-London schools had such high pupil turnover that fewstudents went all the way through the school, he added.
Schools should also be given credit for boosting achievement in ways which are not currently measured, Mr Tomlinson said.
He received a rapturous response from delegates by saying: "Let us not value only that which we can measure. Education is about a great deal more than that. If we ever lose sight of that then I want an early bath.
"If it's not quantifiable then heaven forbid we should try to quantify it. But we have got to find ways of having some way of describing the way we improve these inputs."
School self-evaluation will play a crucial part in the new system, due to come in when the present cycle ends in 2003 for secondaries, 2004 for primaries. But Ofsted will not devise a national system, he said.
lThe Government yesterday delivered a veiled attack on former chief inspector Chris Woodhead's outbursts last year about A-level and degree standards.
Shortly before stepping down, Mr Woodhead dismissed media studies and golf course management degrees as "vacuous", and suggested A-levels needed to be more difficult.
But, in a letter to members of the Commons Education Select Committee, school standards minister Estelle Morris said the standards of degree courses were outside the remit of the chief inspector. She added that if A-level standards were raised, it would be both unfair to new students, and make it impossible to track records over time. It was already possible to differentiate between the most able A-level students through special papers or S-levels.
Elizabeth Passmore, former head of school improvement at OFSTED, has been appointed to replace Mr Tomlinson as the agency's director of inspection.