It is the mystery of the disappearing headteachers. How has a school in a middle-class Oxfordshire town lost another head after going through 10 in just three years?

And why has a school once considered outstanding plummeted from beacon status to being classified as a failure by inspectors?

Dunmore junior’s circumstances and intake are far from challenging. It is on a leafy road in a part of Abingdon with high house prices and many of its pupils go on to private schools.

It was included on Ofsted’s list of outstanding schools in 1998, gained beacon status in 1999 and received another glowing report from inspectors the following year. Dunmore’s website still boasts that it runs courses for other schools to help them emulate its “best practice” work in leadership and management.

But, since Eric Bird stepped down as headteacher in 2000 after 18 years at the school, governors have struggled to find a long-term replacement.

This month, they appointed Martin Lester, a local authority advisory headteacher, as Mr Bird’s 13th successor, though only in a temporary role.

The longest previous incumbent lasted less than two years, while many of the temporary heads were appointed from the ranks of the school’s own senior staff. Four of Dunmore’s assistant heads even worked on a rotating basis as acting heads between January and April 2003.

In April last year, Darren Kenyon became Mr Bird’s 12th successor, though he was only Dunmore’s third permanent head.

Brought in from a pupil referral unit in Swindon, Mr Kenyon’s appointment is understood to have been resisted by Oxfordshire education officers because of his apparent lack of management experience in primary schools.

The test results for the school’s 11-year-old pupils last year were lower than in 2000, but still above both the average for England and for the county. And when inspectors visited Dunmore in October they praised Mr Kenyon for improving morale. However, they still placed the school in special measures for failing to provide an adequate education.

In their letter to pupils, they wrote: “There have been many different headteachers and the school has not improved as much as it should.”

Last month, Mr Kenyon was placed on “indefinite sick leave” in a move approved by the local authority that infuriated parents. The former head is now believed to be considering legal action.

Clive Hallett, Oxfordshire secretary of the National Association of Head Teachers, blames the schools’ governors for the high turnover of heads.

Mr Hallett said the governors had deliberately refused to appoint several strong candidates because they wanted to have a greater say in the way the school was run.

“They then appointed temporary heads from within the school in the face of LEA and NAHT advice,” he said. “This revolving door policy has meant a lack of leadership and consistency.

“I have worked with several of the staff there and they are great people.

But, even with the best will in the world, you can’t have a stable school if there is no leader.”

Parents have criticised the local authority for failing to intervene sooner. Aileen Jones, 40, whose 11-year-old daughter Abigail attends Dunmore, said: “We knew the heads were changing because every time my daughter was in a choir performance there would be a different person standing up in the hall.

“But I think all the parents were surprised by the Ofsted report - I hadn’t noticed any difference in the work Abbie was bringing home from school.

“This school has gone from beacon status to special measures and it is clear that the LEA must be held to account for this.”

Oxfordshire council’s explanation for the school’s high turnover of heads was that the the pool of applicants was too small.

John Howson, an Oxford-based recruitment analyst, said Dumore may have faced problems because it was, unusually, a junior school in an area dominated by all-through primary schools, and suffered falling rolls.

Applicants may have been put off, he said, by the high house prices in the area.

Oxfordshire council said that it had “a very secure strategy for identifying, supporting and improving schools which are of concern”. John Mitchell, assistant to the children’s services director, said that, since the school was placed in special measures, the authority had introduced a very focused action plan to help it.

Stephen Adamson, vice-chairman of the National Governors Council, said the authority might have had difficulties taking drastic action, such as replacing the whole governing body, as the school’s results were above average.

But he said that governors still would usually expect local authorities to intervene earlier. “If the lift is going down it is their job to halt it long before it hits the bottom of the shaft,” Mr Adamson said.

The governing body refused to comment.

* michael.shaw@tes.co.uk