STRUGGLING secondary schools are losing their headteachers at a rate 50 per cent higher than the national average.
One in seven schools at the bottom of national GCSE league tables has advertised for a new headteacher in the past year.
A TES analysis of last-year's lowest-ranked secondaries reveals the pressures schools at the bottom of the pile are under to improve.
Twenty-four, or 15 per cent, of the 157 secondaries with less than 20 per cent of pupils gaining five top-grade GCSEs, have advertised for a new head in the past 12 months.
Nationally, the turnover rate for secondaries is about 10 per cent, according to recruitment expert Professor John Howson, a TES columnist who analysed the figures.
Headteachers' leaders said the figures provided the latest example of the "horrendous" pressures ministers are placing on schools to drive up results rapidly. This, they claim, has become self-defeating because it has made recruiting good heads harder.
Former education secretary David Blunkett announced in March 2000 that schools achieving less than 15 per cent five A* to C would be considered for closure. Twenty-three secondaries are now in that position. The GCSE target rises to 20 per cent in 2004 and a quarter by 2006.
David Hart, general secretary of the National Association of Head Teachers, said: "Headteacher turnover rates like this are excessive. The strategy of placing unacceptable pressures on secondary heads becomes counterproductive, because they know there's a good chance they won't be given sufficient time to turn the school around.
"We think it takes five years. All heads prepared to work in a school in challenging circumstances should be guaranteed that tenure in their contracts.
"If not, good heads just won't be attracted to these schools."
John Dunford, general secretary of the Secondary Heads Association, said:
"The Government has got completely wrong the balance of pressure and support needed to improve these schools.
"It is also concentrating far too much on these so-called floor targets for schools to get above a quarter of their pupils achieving five A* to Cs.
That forces schools to concentrate on borderline pupils, and that's wrong."
Turnover rates could rise still further, Mr Hart believes, with the introduction of leadership incentive grants which give pound;375,000 over three years to governors wanting to strengthen school leadership.
Mr Hart said he knew of three London secondaries which were having their headteacher replaced under the new scheme, which starts next month. One was also having the deputy heads replaced.
Professor Howson thought the turnover rate for headteachers at schools at the bottom of the tables had grown last year.
This was further evidence that schools were suffering "football manager syndrome", in which struggling teams were forced to change their coach in the hope that it would galvanise results.
"It would appear there's pressure on these schools at the bottom of the tables to improve results, and if they don't improve fast enough, the headteacher is replaced. What we don't know is whether headteachers are jumping or if they're being pushed."