Yesterday the biggest secondary teachers’ union SNES, and associated unions representing secondary PE and vocational teachers, called a day’s strike.

And last Saturday teachers from all levels of state education played a major part in demonstrations in support of public services.

Secondary teachers particularly resent a new rule introduced this school year which requires them to stand in for colleagues who are absent for up to 15 days for reasons such as illness or in-service training.

Under the rule, which takes effect from January, the substitute teachers need not teach the subject taught by the absentee. Overtime will be restricted to five hours a week and paid at a higher rate than usual.

But teachers fear loss of independence and argue they are already overstretched. Heads will be reluctant to decide which teachers should stand in if there are no volunteers.

Ministry figures indicate there is an absentee rate of 6 per cent among secondary teachers, with short-term absences accounting for 2.5 per cent of school hours. SNES says more teachers are needed to fill the gaps.

The measure would make teachers who needed time off feel guilty and threaten quality, while doing nothing to solve the problem of long absences which were “too often neglected through lack of tenured replacements or by mismanagement”, the union says.

Another grievance is next year’s education budget. Although this has risen by 6.8 per cent, SNES calculates this amounts to only 1.9 per cent when pensions and salary increases are accounted for.

SNES claims that with the axing of tenured and contract posts, and reduced numbers of trainee teachers, there will be 4,500 fewer secondary teaching posts than needed to maintain educational standards.

At primary level, the leading union SNUIPP said that 800 new posts for primary schools will be much fewer than are needed for the extra 42,700 pupils expected at the 2006 school year.