An investigation into the true scale of “off-rolling” from schools in England has found that more than 49,000 pupils from a single cohort disappeared from the school rolls without explanation.

Researchers from the Education Policy Institute (EPI) said that one in 12 pupils (8.1%) from the national cohort who began secondary school in 2012 and finished in 2017 were removed from rolls at some point, for unknown reasons.

Off-rolling is the practice whereby schools remove difficult or low-achieving pupils from their rolls so that they are not included in their GCSE results, or in order to reduce costs.

Unions said the findings were shocking. Over the five-year period the EPI identified a total of of 55,300 unexplained exits by 49,100 pupils – some of whom will have been moved more than once – and the numbers appear to have gone up in recent years.

For the first time, the research takes into account pupils removed from school rolls due to family reasons, such as moving house, or to a higher-performing school, so the figures represent pupil exits that are likely to have been instigated by schools who may be seeking to improve GCSE results or manage pressures on school budgets.

The research, which claims to be the most comprehensive analysis to date of unexplained pupil exits, also revealed that rates were particularly high in a small number of schools. Just 330 schools, which constitute 6% of secondary schools in England, accounted for almost a quarter (23%) of the total number of unexplained moves in 2017.

According to the EPI, those schools with very high exit rates removed the equivalent of an entire classroom of children from a single year group as they made their way through secondary school between 2012 to 2017.

The EPI’s executive chairman, David Laws, commented: “The size of unexplained pupil moves is disturbing and will raise concerns about whether some schools are ‘off-rolling’ pupils.”

Some students leave through a “managed move”, when a school finds another institution to take them on, while others are encouraged to be home-educated. Unlike formal exclusions, there is no requirement to record the reason why these pupils have been removed from a school roll. A government review is currently under way looking into exclusions and off-rolling, which is due to report imminently.

Dr Mary Bousted, joint general secretary of the National Education Union (NEU), which sponsored the research, said: “The data is shocking, if not surprising. There are nearly 55,000 pupils experiencing unexplained moves, but it is specific groups of students experiencing off-rolling at a far greater rate.

It is urgent that we move beyond the numbers and analyse the real reasons behind these moves Mary Bousted, National Education Union

“It is urgent that we move beyond the numbers, analyse the real reasons behind these moves, and challenge the government policies which are undermining inclusive and high-quality education.”

Report author Jo Hutchinson said: “For the first time, we begin to see the full scale of this problem, having stripped away cases where family decisions have led to school moves.

“Our estimate is that one in 12 children are being pushed around the system, and that this has risen in recent years. We will undertake further research on these trends this year, highlighting prevalence among local areas and groups of schools.”

Geoff Barton, general secretary of the Association of School and College Leaders, said: “The number of unexplained exits uncovered in the research is worryingly high, and the fact that certain vulnerable pupil groups are particularly likely to be affected is also worrying. However, we should keep in mind that many parents make the decision to move or home-school their child for their own reasons and without any pressure being applied.”

Anntoinette Bramble, chair of the Local Government Association’s children and young people board, said: “Councils have serious concerns about the extent of off-rolling and other abuses in the system, which is why they need to be given new powers and funding so they can monitor and take action where necessary.”

The Department for Education said: “No headteacher goes into the job to remove a pupil from school – and no headteacher takes the decision to do so lightly. Schools will typically have gone through a number of sanctions before exclusion is considered, taking into account the welfare of other pupils in the classroom.

“It is against the law to remove pupils on the basis of academic results – any school that does it is breaking the law. We have written to all schools to remind them of the rules on exclusions, and Edward Timpson is currently reviewing how schools use them and why some groups of children are more likely to be excluded from school than others.”