The number retiring has shot up from 5,580 in 1998-99 to 10,270 last year. Early retirement rose in state secondaries by 93 per cent, compared with a rise of 52 per cent in primaries. Most complained of having to juggle poor classroom behaviour with endless new government initiatives.

The figures, which came from a parliamentary question posed by the Conservatives, emerged as Tony Blair and Alan Johnson, the Education Secretary, doubled the number yesterday of aspiring “chief executive” heads and deputies to work in London’s toughest inner-city secondaries.

After a year training 20 teachers under the American- inspired Future Leaders programme, the Government decided to expand the course, having received positive feedback from schools and staff.

The expansion, announced by Mr Blair and Mr Johnson, is designed to recruit more candidates into the classroom from outside education.

The aim of the scheme is to break the cycle of poverty and educational failure in inner-city areas.

With a quarter of all head teachers retiring in the next decade, John Dunford, general secretary of the Association of School and College Leaders, has applauded the move.

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