Proposed changes to the entry rules for JCoSS, which would restrict the number of places guaranteed to local residents and benefit the siblings of former pupils, have drawn protests from parents.

The cross-communal secondary school in East Barnet plans to reverse a policy of cutting priority places for feeder schools.

Patrick Moriarty, its headteacher, writing to parents, said the policy switch was being considered for entry in 2018 because the overall number of places in state-aided Jewish secondary schools in north-west London was expected to increase that year.

He reassured parents that the rise in places would “create space for more — if not all — applicants who seek our distinctive ethos”.

But Karen Yacobi, who lives in North Barnet and has a child at a local Jewish primary school, said her family was “upset” at the proposed reduction in priority places for local people.

This autumn, 50 of the 180 first-year places at the oversubscribed school went to children from its three feeder schools, the Progressive Akiva and the pluralist Clore Tikva and Clore Shalom, while 18 were retained for children who lived closest to JCoSS.

The school is also popular with children from the Orthodox Wolfson Hillel Primary School in Enfield which is only a couple of miles away.

Next year JCoSS will cut feeder school places to 25, while reserving priority for 18 local children.

But in 2018, it wants to add five places for a new feeder school, the cross-communal Eden in Haringey, whose first secondary school applicants will come on stream that year.

At the same time, it wants to reduce the reserved places for local residents to 12.

JCoSS also plans to offer priority to the children of staff who have worked there for two years or more: and to the brothers and sisters of former pupils who have left within the past three years, rather than just one at present.

In his letter to parents, Mr Moriarity said the “main reason” was the expected rise in London Jewish secondary school places in 2018.

“Two Jewish groups have applied to open new free schools by that date, while other alternatives discussed have included the expansion of the existing schools, including JCoSS,” he explained.

“Governors take the view that it is highly likely that there will be significantly more places available by 2018, when this proposed admission policy will take effect.”

He questioned the need for reserving local places because pupils who had entered under that criterion lived on average more than two miles away, which “is not what most consider walking distance”.

But Dr Yacobi, who has a child in Year four at Wolfson Hillel due to go to secondary school in 2019, said, “I have no issue with the feeder system and if they want to offer places to other Progressive schools. But I don’t know why they are doing that at the expense of local residents.”

She added, “Does that mean every time a new free school opens, local residents will suffer?”

In 2019, the first children will graduate from another cross-communal primary school, Alma in Whetstone, which opened three years ago.

Mr Moriarity said one justification for retaining feeder schools was that while children at Orthodox primaries had a choice of Orthodox secondary school, JCoSS was the only school where children from Progressive or pluralist schools could find a continuity of ethos.

But Dr Yacobi said, “Although we send our child to a United Synagogue school, we are not United Synagogue, we are far more Reform. We are not in the catchment area for other [Jewish] primary schools.”

Another parent, Jodi Jackson, who has a son at Wolfson Hillel due to apply for secondary entry in 2018 as well as younger twins there, is unhappy about the entry policy for other reasons.

Following instances of children from Jewish primary schools unable to gain a Jewish secondary place in north-west London, she said, “I am really fearful what’s going to happen when it’s our turn.”

She believes schools such as JCoss, Yavneh and JFS should rely on a lottery system to allocate places rather reserve any for local people. (JFS mostly uses a lottery already).

“It’s grossly unfair that people who happen to live on the doorstep of these schools should get priority,” she said.

Her son wants to go with his friends from Wolfson Hillel to JCoSS.

Although Yavneh is her closest Jewish school as she lives in Arkley, its new entry policy would make it almost impossible for her son to go there.

“I know people who have moved specifically to get their child into a local Jewish school,” she said, “but I can’t afford to.”