The number of poorly performing schools is unacceptably high, with more than 10 per cent of secondary schools providing an "inadequate" education, according to Ofsted's chief inspector.
Christine Gilbert, who took up the post only last month, has used her first annual report to criticise the persistent gaps between the best and worst schools, and said urgent action is needed to improve those failing to make the grade.
However, Ms Gilbert said the overall picture was encouraging. More than 90 per cent of state schools inspected this year were satisfactory and almost 60 per cent were good or outstanding, she said.
The overall proportion of inadequate schools in 20056 - that is those in special measures or with a notice to improve - was largely unchanged from last year. One in 12 of all schools inspected fell into that category, but that rose to one in eight secondary schools, the report found. The number of schools in special measures is down from 242 in 20045 to 208 in 20056.
Ms Gilbert said: "The story is not always positive, however. That is why I am so concerned at the gap between the best provision and that which makes an inadequate contribution to improving the life chances of children.
"We should now be asking questions of those schools or colleges where performance is not good enough and where there are few signs of improvement. Satisfactory can never be good enough."
Ofsted's system of inspecting schools changed significantly in September 2005, with the introduction of shorter and more frequent visits. This increased the number of inspections to the highest ever, at just over 6,000 last year.
The new arrangements, which focus on a school's effectiveness, have "raised the bar, but without putting it out of reach", Ms Gilbert said. Pupils'
achievement was satisfactory or better in 93 per cent of all the schools inspected, which included nurseries, special schools and pupil referral units. Teachers in special schools enjoyed particular success, with 20 per cent of pupils making outstanding achievements.
Academies received a mixed bill of health. Nine were inspected over the year, with only one failing to reach a satisfactory standard. "Given the histories of most of their predecessor schools and their legacy of low achievement, considerable progress has been made," the report said.
However, the schools were also found to have difficulties with staff recruitment and retention, with inexperienced staff a common concern.
Teaching unions gave the report a markedly different reception. Chris Keates, general secretary of NASUWT, said: "Unfortunately, this is the same old tired annual report we have come to expect. Year on year comparisons are meaningless as each year the goal posts change. Consequently, the Ofsted brand has become increasingly discredited."
But John Bangs, head of education at the National Union of Teachers, welcomed the findings. He said: "It is a really measured report in which Christine Gilbert has shown her independence. There isn't a lot of extravagant language about failure. She is only lukewarm about academies.
This is not an endorsement of Lord Adonis's vision of academies holding the key to future success."
The whip hand, page 26
Too many schools are inadequate - 13 per cent of secondaries and 7 per cent of primaries
Eleven per cent cent of all state schools are outstanding, about half are good and a third satisfactory
Pupils' achievement is satisfactory or better in 93 per cent of all schools
Twenty per cent of pupils in special schools make outstanding progress
More than 90 per cent of schools are providing at least a satisfactory quality of education
Almost 90 per cent of nursery schools are good or outstanding, as are almost 60 per cent of primary schools
School attendance is not good enough in one in 10 schools
Behaviour is no better than satisfactory in almost one third of schools
Academies are generally faring well and improving education in deprived areas, although there are problems with recruiting experienced staff.