A major new survey has highlighted the anger among senior school staff over plans to reform their pensions, with nearly two-thirds claiming they are prepared to take industrial action.
Heads' union the NAHT has revealed that 64 per cent of its members would take action to protect the highly prized final-salary scheme, which is under threat from a major review of pensions due to report this spring.
Nearly 90 per cent of the 3,300 largely primary school members taking part in the NAHT consultation said they would not support an end to the current arrangements.
The findings come hot on the heels of a decision by the ATL, a moderate teaching union, that it is to move towards a formal ballot of members over plans to raise contributions to between 9.5 and 9.8 per cent from 6.4 per cent.
The ATL's move was welcomed by the NUT, which is also considering a ballot for industrial action, while the NASUWT has not ruled out strikes.
The Association of School and College Leaders (ASCL), which largely represents secondary headteachers, is also expected to join the throng in the coming weeks as it, too, battles to retain final-salary schemes.
Lord Hutton, who is carrying out a review of public sector pensions to be published next month, has already warned that the schemes are "fundamentally unfair" and reward high-flyers disproportionately.
He is expected to recommend a move towards a career-average scheme, although NAHT general secretary Russell Hobby claims that this would reward fast-trackers who climb to the top early in their careers.
Mr Hobby added: "There is a lot of concern as the final-salary scheme is seen as a right they have earned, not a perk. It's part of the package."
Mr Hobby said the results showed that the association had not "lost its edge", but whether the survey will translate into a formal ballot for industrial action is not yet clear.
The association's formal policy on the Government's proposed changes to teachers' pensions will be decided at its council meeting next month.
The last time the NAHT warned that industrial action was a possibility - a boycott of this year's key stage 2 Sats tests was on the cards last September - it was cancelled in response to a government pledge to carry out a formal review of testing.
The news of the NAHT survey comes as talks between the Government and unions over a proposed 50 per cent rise in pension contributions for teachers are due to start after next month's Budget.
A consultation on the changes is expected to be launched in June.
Mr Hobby said that among members taking part in the survey, there was no general acceptance that teachers should have to pay more for their pensions, despite chancellor George Osborne's claim that savings of between pound;768 million and pound;852 million a year are needed.
However, the NAHT survey did show some willingness among members to pay more for their pensions: 77 per cent said they would accept increased contributions if it meant protecting the scheme in its current state.
NAHT: Sats veterans
- Represents: 28,000 school leaders in England, Wales and Northern Ireland.
- Members in 85 per cent of primary schools and 40 per cent of secondaries.
- Last industrial action: May 2010, boycotted the key stage 2 Sats tests alongside the NUT. Around a quarter of primaries took part.
89% - NAHT members who wouldn't support an end to final-salary scheme.
- Original headline: We'll take action in support of final salary scheme, vow heads