Schools across Britain could face strikes as early as this term as teaching unions meet on Tuesday for a crunch meeting to plan widespread industrial action.
Relations between the unions and the Education Secretary, Michael Gove, already antagonistic, look set to deteriorate further with sources telling The Independent that he is set to make the annual pay award discretionary for schools.
This latest assault on teachers' salaries comes after Mr Gove indicated in December that he wanted to scrap the annual pay increments that allow teachers to climb up the national pay scales, making them instead dependent on headteachers' recommendations.
Leaders of the two unions involved in the dispute – the National Union of Teachers (NUT) and the National Association of Schoolmasters Union of Women Teachers (NASUWT) – are warning the Tuesday meeting could lead to a call for strike action.
Some NUT members want action as soon as possible, preferably before Easter. Plans include an initial, one-day national strike action or a rolling programme of longer stoppages covering different regions at different times.
Either would lead to thousands of children being sent home from school – although exam classes would be exempt from action.
Unions are already on a work-to-rule which they began last year, boycotting a range of administrative tasks in protest at squeezes on pay and cuts to pensions and education spending and this can be escalated into strike action.
Mr Gove has encouraged heads to "fine" teachers for any such action, claiming they are in breach of their contracts and union leaders are warning this could trigger individual strikes.
Members of the NASUWT began their work-to-rule in December 2011 and were joined by the NUT last September.
Since this has involved banning invigilation, refusing to cover lessons for absent colleagues and putting a strict limit on classroom observation of teachers by heads, it has mostly avoided a direct impact on children – unless schools have retaliated by docking wages.
"Where we have escalated action (over 'fines') in individual schools, this has been successful," said Christine Blower, general secretary of the NUT.
She added that the ballot which triggered the work-to-rule allowed for the dispute to be escalated into strike action.
However, the NASUWT would like to see Mr Gove declare his full hand on pay before it moves to strikes.
A more likely scenario, therefore, is that both unions will debate calls for strikes at their Easter conferences - leading to national school shutdowns in the summer.
Mr Gove is not popular with many teachers. So-called Whitehall "attacks" on their pay, conditions and pensions led to unions accusing him of undermining the profession.
Last week, an NUT YouGov survey revealed that most teachers would ask Mr Gove to make resignation his New Year's resolution.