Their employers attacked the National Union of Teachers’ one-day strike over the London cost-of-living allowance saying thousands of teachers in the capital would receive pay rises of up to 17 per cent this year.

Graham Lane, chair of the National Employers’ Organisation for School Teachers, said their pay had risen more in the past decade than that of police, fire officers or other local government staff.

A teacher in inner London who joined in 1997 has seen pay increase by 63 per cent - or pound;10,000 - from pound;16,551 to pound;26,973 over the past five years. The NUT says that the recruitment crisis in the capital will be solved only by higher allowances. In some London boroughs almost one in five teachers is on short-term supply.

Doug McAvoy, NUT general secretary, said: “The employers simply don’t understand the strength of feeling. Even in September, teachers will start their careers 10.8 per cent short of average graduate starting salaries. ” The one-day stoppage on March 14 is in protest at the Government’s refusal to raise London allowances rose by a third instead of 3.5 per cent.

Mr Lane said the strike would not work and would wipe out the allowance rise. The pound;3,000 allowances will increase by pound;105 from April and the one-day strike will cost teachers at least pound;100 in docked wages. London allowances rose by 30 per cent last year.

He said comparisons with police - whose London weighting is pound;3,000 more than teachers’ - were invalid as teachers get longer holidays.

His comments came after Education Secretary Estelle Morris accused the NUT and headteachers’ leaders, preparing to ballot in a dispute over performance pay, of putting at risk progress in schools.

“Industrial action will damage education in London and undermine the status of the profession,” said the Department for Education and Skills.

The last major strike was in 1985 over teachers’ pay and conditions and contributed to the resignation of former Conservative education secretary Sir Keith Joseph.

Heads’ leaders expect almost all London schools to be affected by the one-day strike although many will not have to close.

Other unions will advise members not to join pickets, but to refuse to cover for colleagues.

There are 93,000 teachers receiving London allowances. In a 30 per cent turnout of the NUT’s 41,000 London members 86 per cent supported action.

David Hart, general secretary of the National Association of Head Teachers, expected many NUT members who had not voted to strike to support colleagues.

“My guess is that it will hit some London boroughs where NUT support is strongest, quite hard.”

But an NUT head of year at an outer London primary told The TES he would cross picket lines on Thursday. He expected three other NUT members at his school to do likewise. He said: “I agree with what the NUT is saying, but I’m a professional. The pupils come first.”

Other unions believe it is foolish to embark on industrial action as the Government prepares to do a deal on teachers’ workload.

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