London weighting is set to rise by only 3.5 per cent this year - an increase of pound;105 to pound;3,105 in the inner city and of pound;69 to pound;2,045 in outer London. The “fringe” allowance rises by pound;27 to pound;792.

The School Teachers’ Review Body said, in its annual report, that allowances for the capital were now comparable with those for the rest of the public sector, following a 30 per cent rise last year.

More fundamental changes would have to await the outcome of a shake-up of the funding of local authorities, expected next year.

Linda Taaffe, National Union of Teachers executive member for outer London, who organised a protest rally in Camden this week, said the rise would do nothing to stop young teachers leaving the capital. She said: “The Metropolitan Police receive a pound;6,000 allowance but outer London teachers are paid little more than a third of that. “She is calling on the leadership to back strike action.

NUT general secretary Doug McAvoy has written to Education Secretary Estelle Morris warning that, without a bigger increase in London weighting, staff shortages in the capital will worsen. Unions say that teachers’ allowance is 11 per cent short of the average for all professions.