At least a third of state secondary schools in some of England's towns and cities are under-performing, an analysis of official data shows.
It reveals that children living in the North East and North West are significantly more likely to attend a school that is not up to scratch, compared to their peers in other parts of the country.
A Press Association analysis shows that for the second year running, Knowsley had the highest proportion of secondaries that fell below the Government's floor standard for performance.
In total four of its six schools fell below the required standard, which is based on pupil progress.
This is an improvement on 2016, when all six of its secondaries were considered to be under-performing.
St Helens (50%)
The next two worst places in terms of secondary performance were St Helens and Halton, with half of the schools in each area failing to meet the Department for Education's benchmark.
The analysis also shows that at regional level, the North West of England had the highest proportion of pupils at under-performing schools at 14.8%, up from 13.1%.
Meanwhile, Eastern England had the lowest: 4.4%, up from 3.7%.
Separate data shows that the North East has the highest proportion of schools below the floor standard, with over a fifth (20.9%) failing to make the grade, while London has the lowest at 6.9%.
Figures for other English regions are: North West 19.9%, South West 16.2%, East Midlands 14.5%, West Midlands 10.7%, South East 9.4%, Yorkshire and the Humber 7.6%, East 7.4%.
The Press Association analysis also shows that there are 25 authorities which have no under-performing schools, and 16 of these are in the capital.
Richard Watts, chair of the Local Government Association's children and young people board, said: "There are a number of reasons as to why performance might vary in different areas.
"These include the demand for school places, funding levels and difficulties in attracting the best school leaders and teachers in some areas."