The number of teachers retiring from the profession is continuing to soar, but fewer are leaving on ill-health grounds, new figures show.
Official estimates released by the Department for Children, Schools and Families show 16,850 teachers retired last academic year, up from 14,480 the year before.
It is the eighth successive increase in as many years.
The number retiring on ill health grounds was down by nearly 30 per cent in a year to 1,090, although those taking "premature retirement", with a cut to their pension, rose from 6,640 to 7,460.
The figures bear out fears of an emerging top-end staffing crisis as baby boomers reach retirement age: 3,350 people in leadership roles retired last year. But not all teachers are retiring on particularly healthy pensions, the average annual benefit was just pound;11,100.
The figures also highlighted on-going staffing problems in certain areas of England.
Despite efforts to attract teachers, London and the South East lost 500 full-time teachers in 20042005, the latest year with available figures, while almost all other regions made gains.
The South West, with its brighter weather and attractive countryside, welcomed 260 full-time staff, the highest influx of any region.
The news comes as recruitment analysts have warned of particular problems recruiting middle managers in the capital.
Education Data Surveys, which monitors teaching job advertisements, has revealed that a third of the 74 secondaries looking for a head of maths in the last school year failed at their first attempt.
Eight London schools had to place three or more adverts to find a suitable candidate.
However, the latest figures show the number of newly qualified teachers aged under 30 not entering teaching within a year of graduating has doubled.
In 2004, the figure was 2,700, but had grown to 5,300 by 2005.
Recruitment expert John Howson said: "This shows more than five thousand teachers were persuaded into training and taking the risk, when there could be no job at the end."
The Training and Development Agency for Schools is expected to announce significant cuts to its teacher training targets for many subjects next month.
However, a comprehensive staffing survey, providing the basis for the calculations, will not be released until January.
Mr Howson added: "Clearly there are still big shortages in some subjects such as physics, chemistry, maths and Design and Technology. Other areas such as primary, citizenship and history are over-loaded.
"It seems strange to calculate the teacher training numbers before the publication of the staffing survey."
WHERE THE SHORTAGES BITE MOST
Percentage of head of department posts that had to be readvertised in England and Wales, September 2006 to November 2007
Maths - 29%
English - 28%
IT - 25%
Science - 25%
Business studies - 4%
History - 6%
Drama - 9%
Art and design - 10%
Source: Education Data Surveys.