When it comes to the harsh realities behind the crisis in head teacher recruitment, Tony Elfer, 62, is an expert. Five months after he retired early from a north London primary, he says he wakes up each day with the sweet feeling of “no regrets”.

Forget soft-focus, sentimental Mr Chips. Elfer says that when he said his goodbye to school, what he left behind was a heap of pressure — from anxious parents, endless initiatives in the name of relentless reform and a heart-stopping pace of change.

Terry Farrell, 61, who took early retirement as head of an inner-city London secondary five years ago, agrees that pressures have increased hugely. Matters are made worse, he says, by the problem of rising violence and the knowledge that many children live in horrific circumstances.

“The sheer violence that comes into schools is enervating,” says Farrell. “I had one kid who had been threatening somebody in the playground with a knife.

“He lived with his grandmother and she asked to see me. She was deeply apologetic about it. I told her he had to go. At the end of it, she said she fully understood. And then she asked if she could have her kitchen knife back.”

The problem in recruiting head teachers was highlighted in a survey released by the National Audit Office (NAO) last week. Professor John Howson, who conducted the survey, has since said the NAO misunderstood his data leading to inflated figures.

However, Howson stuck by his central point — that too many schools were having trouble recruiting heads and were often having to fall back on acting heads who had applied for the job but been rejected.

The NAO said the shortage was responsible for the fact that despite the government spending £1 billion on failing schools last year, one in eight pupils are not getting the education they deserve.

Church schools were among those with the worst recruitment problems. For Roman Catholic schools the re-advertisement rate was 59%. Schools in London — where primary heads can earn up to £70,000 and secondary heads up to £100,000 — also had severe difficulties, with re-advertisement rates running at 50%.

The problem is not confined to the state sector. Brenda Despontin, incoming president of the Girls’ Schools Association, which represents 207 independent schools, is to urge ministers to set up an all-party commission to work on recruitment proposals.

Elfer, whose last headship was with the high-achieving St Joan of Arc Roman Catholic school, says his own post had to be advertised twice before it was filled.

“I think the level of anxiety in the country about education has become very intense,” says Elfer. “Dealing with parental complaints is the thing I am happiest to have left behind.”

Former secondary head Richard Fawcett now works as a consultant to recruit heads. He says the decline in interest in headships is connected to rising responsibilities. “I know one head who works from 7am to 8pm ,” he says. “He takes Saturday off but works Sunday. Is that healthy?”

Stephen Szemerenyi, 62, was head of Finchley RC high, in north London, until 1999. He points to the growing vulnerability of heads. “We have got an increasing number of people who are simply sacked on the basis of a school inspector’s visit,” he says. “People who are in senior management ask themselves, ‘Why do I want to do a job that is so challenging when if I don’t make the requisite grade I will be sacked?’ ”

It’s a question to which fewer and fewer potential heads seem able to find an answer.

Additional reporting: Mary Braid