Some 17 per cent of secondary schools were last year either at their student capacity limit or over it - compared with 15 per cent in 2017, according to figures released today.
That was despite an extra 50,000 secondary places being created last year.
The Department for Education figures published today forecast an increase of more than 120,000 pupils between 2018-19 and 2019-20.
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The DfE report states that secondary student numbers will continue to rise each year reaching around 3.8 million by 2025-26, compared with around 3.25 million last year.
Secondary school student numbers to rise
Julie McCulloch, director of policy at the Association of School and College Leaders, said there was a challenge in dealing with “a big demographic change” as a bulge in pupil numbers moved from primaries to secondaries.
She said: “These statistics suggest the number of crowded primary schools rose as pupil numbers increased over the past decade but is now reducing, while the number of crowded secondaries fell but is now increasing as the pupil bulge moves into this phase.
“This re-emphasises the importance of well-coordinated local place planning to meet this demand. This will be particularly crucial in providing secondary places over the coming few years as the number of pupils in this phase continues to rise.”
For primaries, around 30,000 new places were created last year, yet 20 per cent of primary schools were still either at full capacity or over its capacity - however, that compares with 23 per cent in 2017.
The demand for primary places is still expected to rise and to peak in 2021 at around 4.6 million pupils, from just over 4.5 million pupils last year.
The report states that more than a million new school places have been created since 2010. It adds: “Local authorities have reported that they are planning to create 118,000 additional places by 2021-22. Local authorities also plan to create 11,000 temporary bulge places to accommodate large cohorts, and remove 20,000 places by 2021-22. Taken all together, local authorities are planning a net increase of 109,000 places.”