Ms McLean was one of 616 heads and deputies who became additional inspectors from September 1995 onwards after the primary inspection schedule began to slip.

But more than two years after becoming an AI, Ms McLean has not returned to her old post. Instead, she has become a primary adviser with Cornwall County Council, which also carries out OFSTED inspections in other parts of the country.

And Ms McLean, who was a head for 10 years, is far from being alone in deciding that an inspector’s life is preferable. OFSTED has found that, even though the emergency inspectors’ scheme has been wound up, 39 per cent of AIs are continuing to treat inspection as their main career. A further 5 per cent are working for local education authority advisory services. Just 38 per cent have returned to their former schools and 5 per cent have obtained new headships. The remainder have either retired or chosen new careers.

Ms McLean says that working as a registered inspector re-awakened a passion for teaching that had been slightly dulled during her last years as a head, when she had been forced to focus on school finance and management. “The joy of the AI project was seeing the emphasis placed on standards and the importance of teaching and learning,” she explains.

John Francis, former head of Stramongate primary in Kendal, resigned as head a few months after starting his secondment.

“I had been a head for 18 years and there seemed to be limited opportunity for career development or in-service work,” he says.

Mr Francis, who now lives in Worcester, is a registered inspector and is on the books of two companies that bid for inspection contracts. He divides his time between OFSTED inspections (last year he did nine) and working as a member of school-imp rovement teams that carry out follow-up visits to schools.

Financially, he is slightly better off than as a head, but his work patterns have changed considerably. Although most of the schools he visits are in the Midlands or the South, he often spends nights away from home.

The fact that so many heads decided to become inspectors was one reason why the project was wound up a year earlier than planned in September 1997.Sue O’Sullivan, an HM inspector who managed the project, says OFSTED had not expected so many heads to choose inspection as their main career. “They obviously found the option of looking at the national picture very attractive,” she says.

But not everyone from the AI project found a new job. Ray Crocker, head of Roxbourne middle school in Harrow, north London, returned to his post after a one-year secondment. Initially, he found it difficult settling back into school: “I had become used to working for myself, but I missed the sense of community as well as the creative side of running a school. ”

To retain his status as a registered inspector Mr Crocker must conduct at least one inspection each year. Last year he did three. “I found it very hard work as I still had the school to run. Most of the writing was done during the evening and weekends.”

Mr Crocker has drawn on his inspection experience for a project at Roxbourne that led to an improvement in key stage 2 science results. And this term he faces another challenge - helping his school prepare for its own OFSTED inspection. “I may have been through it all before as an inspector,” he says, “but now I have to persuade my staff to recognise what is required.”