Many Year 6 pupils are still without offer of a secondary school place for autumn, despite the official deadline for allocating places having passed last week.
Around 450,000 children were supposed to out what their new school would be on National Offer Day, on Friday.
However, Tes understands that some local authorities are still struggling to allocate places, and that a spike in the birth rate in the 2000s, which is now making its way through the school system, may be having an effect.
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Campaigner Rhys Madoc, who is organising a protest in St Albans this Saturday over the school places “crisis” said on Facebook that a total of 186 children in Hertfordshire had been told they would not receive a school place “at all” in September.
He added: “This is not the result of a sudden influx into the area but has been a known issue since the children this age were born in 2008.”
Meanwhile, in the London Borough of Barnet, a spokesman said some pupils from the borough had not been allocated places after more than half the applications came in from outside.
He said there had been a “very high demand” owing to the high attainment of schools in Barnet, but the borough’s growing population was also a factor.
Based on analysis of birth rates and the number of children leaving primary school, the Good Schools Guide estimates 606,000 applied for places this year - an increase of 23,000 on 2018.
According to the Association of School and College Leaders, the number of pupils in secondary schools is rising and is expected to increase by 428,000 over the next seven years.
A survey by the Press Association revealed that almost two-thirds of local authorities were beginning to feel “a squeeze,” on school places, with 22 out of 34 local authorities that responded to the survey reporting an increase in demand for places.
A spokesperson for Hertfordshire County Council said 7 per cent of Year 6 pupils were still without secondary school places but all children would be allocated a place by 18 March.