The scramble to find acting heads from new sources is a direct result of the crisis reported in last week’s TES, with around 1,000 schools starting the new term without a permanent headteacher.

For now, however, with many members of the profession evidently unwilling to take on the responsibilities of being a head or a deputy - vacancies for secondary deputy headships rose by 52 per cent this year - many local authorities and governing bodies have had similar difficulties finding staff to act as temporary heads.

The new Brighton and Hove education authority, which has acting heads in four primary schools, has taken the step of appointing an assistant director of education, Peter Walker, as acting head of Longhill school, an 1,100-pupil mixed comprehensive.

A spokeswoman for the council said that Mr Walker - whose last school job was as a deputy head nine years ago - was simply in as a temporary measure until a suitably experienced person could take on the acting headship.

“Obviously he wants to get out of there as quickly as he can because he’s got his main job to do,” said the spokeswoman. “An advert is due to come out this term, but deputies and heads have got to give up to two terms’ notice.”

A more common response to the problem is to use heads recruited by supply teaching agencies.

Capstan Teachers, which already has more than 1,000 supply teachers on its books, said it advertised for supply-heads after approaches from LEAs.

Roger Hurn, director of Capstan’s “interim headteacher service” said that more than 100 headteachers - most of whom took early retirement this year - applied, and 18 were taken on.

Capstan is now providing heads for two primaries, in Islington and in Harrow, and a deputy for a primary in Hackney. Four more schools have already requested supply heads for next term.

Mr Hurn said that the service was necessary partly because governors were increasingly unwilling to release their own staff to be acting heads for nearby schools.

“Now governors have the final say they’re quite loath to release someone from their school to go and help out a rival school,” he said.

“If both schools are going to be in the league tables it’s not necessarily in the governors’ interests to help out.”

The TimePlan agency, is also offering to supply heads.

Kerry George, national salaries officer of the National Association of Head Teachers, said: “An acting head is not like a doctor’s locum. You’re not dealing with sprained ankles - you’re dealing with the ongoing education of children.

“Both of these new measures sound like the responses of education authorities and governing bodies desperate to keep schools open.

“And we also fear that if the employment status of these agency heads is as unclear as the employment status of supply teachers then the arrangement could be in breach of the law.”

She added that she feared that governing bodies would have to pay inflated rates in order to attract acting heads .

Mike Walker, of the Local Government Management Board, said concerns about legal problems with agency heads had been passed on to the Government, without response.

A spokeswoman for the Department for Education and Employment said officials from the department had spoken to four agencies offering ‘locum heads’ after seeing their press advertisments.

“The department knows that schools need to get head teachers and this is something we’re looking at,” said the spokeswoman.

“There’s no problem with using heads supplied by agencies,” she added.