JFS is planning to decide within a fortnight whether there is enough demand to justify opening an extra class this September.

It says, along with other schools in north-west London, that it is trying to determine how many children on waiting lists have been left without any Jewish school after the first round of offers was made last week.

A spokesman for JFS said “within the next two weeks we’ll know where we stand and then we’ll be able to announce what the outcome is”.

While JCoSS this year expanded its Year-seven entry from 180 to 210 for 2017, JFS promised to add an extra 30 places if demand warranted it.

Victor Arotsky, whose daughter, Annie, a pupil at Hasmonean Primary School, is one of those without a place after applying to JFS, Hasmonean High and Yavneh College, said: “We’re slightly anxious but not too worried because we know there are multiple rounds of offers and there is talk of having an extra class.”

Kirsten Jowett, headteacher of Wolfson Hillel Primary School, was aware of 10 children in a similar situation in her school.

She said she was trying to reassure parents it “should be all ok in the end” as places open up at schools over the next few months.

Speaking to colleagues in other Jewish primaries, she believed the picture to be broadly similar to last year.

But Susy Stone, headteacher of the Progressive Akiva School, which sends around two-thirds of its children to JCoSS, said the number of children without a place had increased to three or four this year. “Last year we had one child who didn’t get a place in the first round of offers but got in the second round.”

JCoSS had reduced the number of children guaranteed places from feeder schools such as Akiva this year, she pointed out.

Between now and June, Jewish schools will hold several more offer rounds as rejected places become free. It is not known how many families with a place at one school will be hoping to switch to another.

Last year JCoSS and JFS alone offered nearly a hundred places between them after the first round. Neither opened a bulge class in 2016 (although Yavneh College did so just for that year).

One parent, whose son was unsuccessful with applications to JCoSS and JFS last week, said he would be “happy to accept” the place offered at a local non-Jewish school.

Matt Plen, chief executive of Masorti Judaism, said. “We’re lucky we have really good schools on our doorstep.” But if a place came up at JCoSS, where his son Micha remains on the waiting list, “we’ll consider it.”

Despite its expansion, JCoSS has a waiting list of more than a hundred children whose parents put it as first choice. The school enjoyed a record number of applications, up from 695 in 2016 to more than 700 this year.

A JCoSS spokesman said: “Although there are still a large number of students on our waiting list, it is very early days and we expect a lot of movement in the coming weeks.”

The extra class for 2017 was “a very significant and necessary addition for school places in the community”.

The number of those accepted as siblings of pupils had risen from 96 to 103. But there was tougher competition for the 18 places JCoSS allocated to those living closest to the school; whereas last year the furthest applicant awarded a place on that basis last year lived 1.78 miles away, this year it was only 0.99 miles.

JCoSS said 56 places this year had been awarded through random lottery.

According to Barnet Council, 158 out of the 180 places at JCoSS last year went to those who put it first choice, with 12 second-preference applicants and three, third. But the vast majority of entrants to Hasmonean in 2016 put it as first choice — 184 out of 190.

One mother of a child without a place at a Jewish secondary, who did not wish to be named, said: “It is the second time it has happened because he originally didn’t get a place at primary school. He only got a place there in the second year and one of the reasons we moved him to a Jewish primary was we thought it make easier to get into a Jewish secondary school.”

She said she was trying to maintain “a positive attitude” and “not let anxiety creep into our son”.

Meanwhile, the private Immanuel College expects its entry for 2017 to exceed 80, as last year. Families offered places were asked to pay a non-refundable deposit of £2,000 by Monday this week, otherwise offers would going to those on its waiting list.

Even if JFS opts for an extra class, places will not automatically go to those without a Jewish school; they will still have to be allocated in accordance with the school’s entry policy.