Jewish schools will be undersubscribed

Mr Glass said: "We have one or two places still open where this time last year we had a long waiting list and more than 40 appeals."

He added that taking London's five state-aided mainstream Jewish secondaries as a whole, "there are more places than demand for them".

Predictions two years ago by the Jewish Leadership Council that a rapid increase in places would lead to more non-Jewish pupils attending Jewish schools appear to have been borne out far more quickly than expected.

At King Solomon High School in Essex, only 90 of the 150 first year entrants in autumn are Jewish, whereas the Jewish intake was 115 out of 122 last year. The school believes that Jewish figures this year reflect an unusually low number of Jewish children coming from one of its feeder schools.

JCoSS, which has room to take 180 pupils each year, has capped its entry at 150 and says it is close to reaching that target this year, with three non-Jewish pupils among its new recruits.

The new school says it has helped to expand the number of children opting for Jewish day schooling overall because two-thirds of its entrants in autumn will come from non-Jewish primaries.

Of the remaining third coming from Jewish primary schools, 55 per cent come from London's three Progressive or pluralist primaries, with the remainder from Orthodox schools.

Lara Samuels, who this week attended an induction day at JCoss for new pupils with her 10-year-old son Josh, a pupil at a non-Jewish primary school, said: "I like the open-mindedness of JCoSS. I would not have sent my son to a Jewish school without it. My older daughter is in year seven at a local state school and she would have loved to have gone to JCoSS."

The longer-term picture is uncertain because there is rising demand for new Jewish primaries which could produce more Jewish applicants for secondary schools over the next few years.

On the other hand, the falling Jewish birthrate - outside the strictly Orthodox community - could lead within a decade to other Jewish secondary schools having to follow King Solomon and taking larger numbers of non-Jewish pupils.

After last year's Supreme Court ruling, Jewish schools can no longer give priority to Jewish children simply because their parents are Jewish; they now need proof of Jewish practice. So Jewish children who lack the certificates of practice now required by schools can no longer be guaranteed a place even if a school has vacancies.

The reason the mainstream Jewish secondary school system expanded so rapidly - from three to five state-aided schools in just four years - is largely due to the problem of children whose Jewish status was denied by the Orthodox rabbinical authorities. When there was a shortage of places at the then three Orthodox schools, such children would be rejected because priority was reserved for children considered Jewish according to Orthodox rules.

JCoSS, which was set up to have a broader entrance policy to include such children, had been planned to start in Hertfordshire. But the Orthodox Yavneh pipped it to the post, opening in the area in 2006.

Supporters of the two projects did hold talks about joining forces in a single school but could not agree on admissions policy.