Secondary school class sizes have risen for the fourth consecutive year, according to new figures published by the Department for Education.

The percentage of pupils in classes with more than 30 students is at the highest it’s been in the 13 years for which data is shown.

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In January 2019, 13 per cent of pupils in English secondary schools were in classes with over 30 pupils, compared with 9.6 per cent in 2015.

Geoff Barton, general secretary of the Association of School and College Leaders, said the rise in the proportion of pupils in classes of more than 30 since 2015 meant “that the number of pupils in large classes has increased by more than 118,000 in that time”.

“This increase in class sizes is a direct result of real-terms cuts in school funding,” he said. “Class sizes have increased because schools have had no alternative other than to reduce the number of staff they employ at the same time as pupil numbers are rising.

“Without improved funding, this situation will worsen. The two contenders for the leadership of the Conservative Party should be worrying more about schools than about tax cuts.”

The average class size for state-funded secondary schools in England was 21.7 in 2019, compared to 20.1 in 2015.

At state-funded primary schools in England, average class sizes have remained stable at 27.1 since 2016.