Too many children from poor homes are receiving an education that is "patently inadequate", according to a stark warning issued by Ofsted this week.
Schools serving the most deprived areas have failed to improve as quickly as those in other parts of the country, reinforcing disadvantage, said Christine Gilbert, the chief inspector.
In her third annual report, Ms Gilbert said there was reason to celebrate overall improvements in schools and further education. But she criticised the persistent achievement gap between rich and poor.
Almost one in 10 secondary schools are inadequate, a number that has barely shifted over the previous year, despite investment and policies aimed to improve schools with the lowest results. Ms Gilbert also criticised the number of pupils that leave primary school without having reached expected levels in English and maths.
It is the first annual report since Ofsted's remit was increased to include the inspection of childcare, social care and adult learning.
Ms Gilbert's message about the poorest and most vulnerable being failed by the system was consistent across all the areas for which Ofsted is now responsible.
Serious concerns were raised that lessons are not being learned from the deaths and serious injuries of children in care, a criticism all the more damning in light of the death of 17-month-old Baby P.
"This report leaves me encouraged by the recognition that so much is going well for so many children," said Ms Gilbert, "but frustrated that there is still too much that is patently inadequate and too many instances where the rate of improvement is unacceptably slow."
In schools, almost two thirds of the 7,500 inspected between September 2007 and July 2008 were rated good or outstanding, an increase of 5 percentage points from two years ago.
The number of inadequate schools overall has dropped from 8 per cent to 5 per cent, but most of those improvements have been made in primary schools, rather than secondaries. More than 20,000 pupils are still completing their GCSEs in schools that are causing concern.
"The problems in secondary schools are difficult, but the numbers that are inadequate are far too high," said Ms Gilbert. She praised the impact of Teach First for attracting high quality graduates into teaching in challenging schools, but criticised the fact that only 21 per cent of children eligible for free school meals achieved the GCSE benchmark last year, compared to 49 per cent of other pupils.
Changes to the inspection regime, due to be introduced next September, will help address the problem, Ms Gilbert said. There will be increased inspections of struggling schools, while reducing the burden on schools doing well.
There will also be an increased focus on schools that are not improving. It follows a Government promise last week for Pounds 40 million of additional support for hundreds of "coasting" schools.
Miriam Rosen, Ofsted's director of education, said there was concern at the "volatility" with which some schools moved between being failing and satisfactory. More schools escape special measures more quickly than before, but others slip to replace them.
"This is often because leadership isn't good enough," she said. "There is quite a high level of turnover in leadership of schools in special measures. They will frequently have a new headteacher."
Christine Blower, general secretary of the National Union of Teachers, said the performance gap between schools in rich and poor areas would not be closed by the chief inspector's criticisms. "It can't be achieved by lambasting schools in the toughest areas," she said. "That simply creates demoralisation and discourages committed staff."
FAILINGS ON ABUSE
Child protection services are failing to learn the lessons from the "worst cases of abuse", Ofsted warned this week. More than 40 per cent of the reviews carried out following the death or serious injury of a child were inadequate, inspectors said. There are often long delays, meaning that the potential to learn is "severely restricted", according to the inspectorate's annual report.
The quality of children's homes was also called into question, with 8 per cent judged to be inadequate.
Christine Gilbert, chief inspector, said everyone involved in child protection had to "take stock" and improve the system.
13% - Outstanding
50% - Good
33% - Satisfactory
4% - Inadequate
17% - Outstanding
40% - Good
34% - Satisfactory
9% - Inadequate
15% - Outstanding
49% - Good
32% - Satisfactory
5% - Inadequate.