Brenda Despontin, president of the Girls’ Schools Association, which represents some of the biggest single-sex private schools in the country, said the independent sector was not immune from concerns over headship.

Last year, a third of all schools in England and Wales failed to appoint a head when they first advertised a vacancy, indicating a deepening crisis in school leadership. Professor John Howson, recruitment analyst, said the findings, from an annual survey of headteacher job adverts, were the worst in 21 years.

Dr Despontin, head of the pound;16,713-a-year Haberdashers’ Monmouth school in south Wales, said the private sector had not yet been hit by the same shortages.

But she said it had to do more to encourage teachers to consider a career as heads or face contributing to the national decline.

“In recent times headship has become increasingly demanding and it is no longer enough for a head to be simply an excellent subject practitioner,”

she said. “They have to be personnel officer, a finance officer and have the legal skills to lead what often amounts to a multi-million pound enterprise.

“Keeping good headteachers in their post is vital, but so is the drive to recruit the next generation of leaders. Without it, we will increasingly see schools without heads or some appointing leaders ill-equipped for headship.”

More than 2,600 schools in England and Wales advertised for a head last year, the bulk of which came from the state sector. At least 1,000 jobs had to be re-advertised and the proportion of posts being re-advertised increased between 2004 and 2005 from 27 per cent to 36 per cent in secondaries and 37 to 38 per cent in primaries.

Last month Dr Despontin, the first Welsh president of GSA, launched a initiative allowing teachers to shadow private school heads, in an attempt to address the shortages. Almost 20 heads have so far volunteered to take part. A telephone support line has also been established by the GSA for its 207 members, which include schools such as the pound;23,400-a-year Roedean school, Brighton. Dr Despontin told the TES that she will also use her year as GSA president to urge ministers to set up an all-party commission to work on recruitment proposals.

Her comments follow those of Andrew Boggis, new chairman of the Headmasters’ and Headmistresses’ Conference, which represents more than 240 top private schools, who said that the private sector faced increased competition for heads from the Government’s new academies, independent state schools.

Professor Howson said: “There is little evidence of how the heads shortage is affecting the private sector, but it is certainly true that most independent schools will not be able to match the pound;100,000-plus salaries that are now becoming the norm for headteachers of large state schools.”

Girls’ Schools’ Assocation 0116 254 1619.