The number of children graduating from Jewish primary schools in London is set to rise by more than a quarter in just six years, adding to the squeeze on places at the community's secondary schools.
The educational agency Partnerships for Jewish Schools (Pajes) has predicted a shortfall of 135 places at Jewish secondary schools in north-west London in 2022.
But Pajes believes that the numbers may still not be enough to justify the opening of a new secondary school, without more non-Jewish pupils being admitted.
According to a Pajes survey of 30 London Jewish primaries across the religious spectrum, the number of students leaving each year will leap from 918 this year to 1,193 in 2022.
It estimates that 90 per cent of pupils from Orthodox primaries and 70 per cent from cross-communal primaries will apply to a Jewish secondary school.
But the swell will already start to be felt in three years' time with an estimated shortage then of more than 90 places.
Former JFS chairman Michael Glass, who carried out the survey, told the UJIA education research conference in London last week that in 2019, "we come to a very significant challenge because there is not enough to open a new school and there are too many children to do nothing. That is the sort of dilemma we are in."
Two groups have announced plans since the beginning of the year to bid to open a new Jewish secondary free school in north-west London for 2018 - Kedem High School and Barkai College.
Eli Gaventa, a backer of the modern Orthodox Barkai school, said that his group had received an "incredible response" to an online survey and a series of open evenings for parents. "We feel that every Jewish family who wants a Jewish
education for their child should have the opportunity for that child to attend the school that best fits their needs," he said.
But Mr Glass believed that a new school could eventually leave JFS and JCoSS with too few Jewish children to fill their places.
Although a shortfall of 30 to 50 places is forecast for this year, this is expected to be covered by extra places being offered by Yavneh College and Hasmonean High School beyond their usual maximum.
Pajes chief executive Rabbi David Meyer said that "things look considerably better than last year", although Charedi schools in the area were facing additional pressures.
JFS said that the number of appeals to the school were "substantially lower" than last year, suggesting less pressure within the mainstream Jewish secondary system.
But some parents are still facing a nerve-wracking wait. Kelly Ifrah from Watford, whose son Yohann, a pupil at Rosh Pinah Jewish Primary School, is one of those on the waiting list of several Jewish secondary schools, said that she knew of 22 children in the same boat.
"We must make sure no one is left without a place at a Jewish school in September," Mrs Ifrah said.
Jonathan Rabson, executive director of the National Association of Orthodox Jewish Schools, said that around a dozen boys were still without places in north-west London Jewish secondaries in the right-wing Orthodox sector and a similar number at primary level.
Pajes has commissioned further research over the next few weeks to determine the likely applications to Jewish secondary schools from children at non-Jewish primary schools.
Predicting future demand and trying to find a solution was "a very complex problem to grapple with", said Mr Glass. "The community can't afford to get this wrong, but we haven't necessarily got it right in the past."