Nearly two thirds of the secondary schools in England have had to increase their class sizes because of a lack of funding, research reveals.

A new study by the School Cuts coalition of unions found that 62% of secondary schools in England have increased the size of their classes in the last two years.

The coalition, which includes teaching unions such as the National Education Union (NEU) as well as UNISON, GMB and Unite, argues this is the result of a funding shortfall of £500m a year for 11–16 year olds between 2015/16 and 2019/20.

The expansion of classes is also the result of what the coalition describes as ‘deep cuts’ to sixth form funding, which amount to over 17% per pupil since 2010.

‘We have repeatedly warned that schools have had to increase class sizes because of funding pressures and here is yet more evidence that this is the case,’ said Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), another member of the coalition.

‘It is the last thing they want to do but they have no other choice because they have to reduce staffing numbers and that inevitably affects the teacher-to-pupil ratio.

‘Larger classes mean less individual support for students, and put more pressure on teachers at a time when we desperately need to reduce workload.’

Paul Whiteman, general secretary of school leaders' union NAHT, emphasised the fact the majority of schools faced ‘real-terms budget cuts’ compared to 2015/16.

‘The Government's own figures show that an extra 654,000 school places will be needed in England by 2026, to meet the nine per cent rise in pupil population,’ he said.

He continued: ‘91% of schools face real-terms budget cuts compared to 2015/16 at a time when costs are rising and pupil numbers are growing.

‘Not only that but the cuts to front-line classroom posts combined with a rise in pupil-to-classroom teacher ratios, mean bigger classes and less individual attention for children.’

Jon Richards, UNISON head of education, added: ‘It’s a sorry situation when rising class sizes are happening in sync with cuts to school support staff.

‘Fewer support staff means more work for already hard-pressed teachers. Over the past five years, secondary schools have seen a 10% cut in school technicians and an 8% cut in teaching assistants. 

‘This is a double whammy for vulnerable and disadvantaged pupils, who can face greater challenges in larger classes and for whom support staff are a lifeline.’