Headteacher recruitment is continuing to plummet, jeopardising Government attempts to raise the standard of school leaders, according to new figures.
Two-thirds of primary schools got only 10 applications or fewer when they advertised for heads last year. In small primaries, this figure rose to five schools in six, a survey for the National Association of Head Teachers found.
The situation is worst in London - 43 per cent of the capital's primaries failed to appoint after their first advertisement.
A third of schools in the affluent Home Counties were unable to appoint, and a quarter of primaries in the rest of the country.
NAHT general secretary David Hart said potential candidates were increasingly deciding the extra pay was not worth the responsibility of headship. His union has submitted a 17 per cent pay claim, saying that is how far heads have fallen behind comparable managerial posts in the public and private sector.
The union also claimed applications for the new National Professional Qualification for Headship were too low - 4,000 in its first year and 750 last term - to produce a decent pool of candidates when the Government made the NPQH mandatory.
"Prospective heads don't see the qualification as worth going for because they can see the pressure heads are under," Mr Hart said. "That relates to a whole raft of issues including lack of administrative support.But they also see that promotion doesn't lead to a decent pay increase."
The Teacher Training Agency said no targets for the NPQH had been set but numbers were "very healthy".
The survey of headship recruitment, by John Howson of Education Data Surveys, covered almost half of the 2,500 schools that advertised or re-advertised last academic year.
It found the average London primary received only five applications, Home Counties schools received seven and schools in the rest of the country received nine.
The trend is steeply downwards. Among the smallest primaries, half failed to get more than five applicants, compared to only a quarter a year ago.
Even in the largest primaries those getting more than 10 applications, fell from 56 per cent to 34 per cent.
Those that failed to appoint cited the poor quality of applicants as the main reason for leaving the posts empty.
A Government spokesman said that ministers recognised the problem, particularly in London. The Green Paper would tackle it in a "fundamental way".