Parents of JFS pupils have inevitably been left guessing by this week's announcement of head teacher Jonathan Miller's leave of absence.

Governors have not revealed the reasons behind it nor given any hint of when or whether they expect him to return.

But the decision to use an outside consultant, Debby Lipkin, to help manage the school in the interim is unusual in one sense.

JFS has maintained a proud record of recruiting leadership from within its own ranks. Mr Miller, who was a deputy head at the school before beating external applicants to the top job in 2007, followed in the footsteps of Dame Ruth Robins and before her Jo Wagerman, both of whom were internal appointments.

Ms Lipkin is part of the school improvement team for Olive Academies, a multi-academy trust whose mission, according to its website, is to "create enriching opportunities for young people struggling to succeed in education".

Governors have not revealed the reasons for Mr Miller's absence

Judged by exam results, JFS is most certainly not a school that is struggling. At A-level, it was the best-performing Jewish school last summer in terms of the average grades per students.

It also attracted a highly value-added score for GCSE, meaning that pupils had made significantly above-average progress since the time they arrived at the school.

This year's sixth-formers have also received a record number of Oxbridge offers.

But there was no doubt that the school was rocked by a critical Ofsted report two years ago after an unexpected inspection.

Having been rated as an "outstanding school" in 2009, it dropped two inspection grades to a school "requiring improvement".

Mr Miller described the Ofsted report as "not an accurate reflection of the school we know".

A follow-up inspector's visit a few months later recorded that the school's leadership had acted "resolutely" to make improvements. It noted that the local authority had contracted an unnamed "independent school improvement adviser" to work with JFS.