England's children are victims of a postcode lottery in gaining a decent education, with some facing a less than 50% chance of attending a good school, the Ofsted chief inspector has warned.
More than two million children are still being taught in schools that are not good enough, and a youngster's chance of attending a high-quality school is often too dependent on where they live, Sir Michael Wilshaw said.
In his first annual report, Sir Michael said there are marked inequalities in England's education system that must be addressed.
"It is absolutely a postcode lottery and we are never going to get a world class system unless we reduce these wide variations," he said.
While the overall quality of schools has improved in the last few years, this is not consistent across the country.
A primary school pupil in England has, on average, a seven in 10 (69%) chance of being in a good or outstanding school, the report says, but in some parts of the country, a child has a better than 90% chance, and in others a less than 50% chance.
Sir Michael points out that there is no link between access to a good primary school and how rich or poor an area is.
Some of the poorest areas in the country have high numbers of good and outstanding primaries, while there are richer areas that are performing badly.
Oxfordshire, which is not considered an area of high deprivation, is among the 20% of local authorities with the lowest proportions of pupils attending a good or better primary, the report says.
Sir Michael said: "If we aspire as a nation to move towards a world leading system, we have to reduce these serious inequities across the system."