The number of teachers leaving their jobs has shot up by nearly 40 per cent in the last year, according to new official figures.
The increase confirms fears of a growing recruitment crisis in schools - expected to be especially serious for headteachers' posts - and coincides with a fall in the number of young people applying for teacher-training courses.
The new figures, released by the Department for Education and Employment, will also add urgency to the Government's Pounds 1.5 million campaign to persuade people to choose teaching as a career.
They show 21,300 teachers quit in the first nine months of this year, compared with 15,400 in the same period last year. The total includes 2,600 heads, an increase of more than 50 per cent on last year.
The exodus is thought to be mainly due to teachers rushing to beat a government clampdown on early-retirement deals and is unlikely to be as serious next year.
The National Association of Headteachers claimed the figures vindicated its warnings of serious shortages.
Last week the union accused local government employers of playing down the crisis. The union wants heads to receive a 10 per cent pay rise to attract more recruits.
This week Graham Lane, leader of the employers - the Local Government Management Board - denied there was a shortage. He pinned the blame for the exodus on local authorities being too ready to agree early-retirement packages.
"This is a one-off because of the deadline on early retirement and it won't happen agan next year," he said.
Commenting on the latest figures, Kerry George, head of pay and conditions of the NAHT, said: "This is a huge increase which underlines the fact that we are facing serious difficulties recruiting the people we need."
Figures released by the Graduate Teacher Training Registry, show that applications for next year are down by more than 10 per cent on last year, from 15,172 to 13,500. Shortage subjects including maths are among those hardest hit.
The DFEE figures show the number of deputy heads quitting rose from 1, 400 in the first nine months of last year to 1,800 this year. The number of classroom teachers leaving rose from 12,300 to 16,900.
Analysis, page 25