If the National Education Union votes to strike today - which seems likely - that will be a huge headache for the government, and will be massively disruptive to parents and the functioning of the economy.
It will be the biggest vote in this winter of discontent by any group of public sector workers.
There are 350,000 teachers eligible to vote and a mandate for strike action requires a huge 175,000 to have voted either yea or nay and 140,000 to have voted yes.
If that many teachers have voted to strike to reject a 5% pay offer - and we’ll know for sure at 5pm - that is astonishing, given that under the government’s rules all votes have to be by post, and there’s been a postal strike!
It shows the scale of teachers’ unhappiness, not just about how inflation has been significantly reducing their living standards, but also about chronic teacher shortages caused in part by the perceived mismatch between their pay and duties.
The first day of action (of potentially many) would be 1 February, which is the day when tens of thousands of other unionised workers in the public sector will be striking in a day of coordinated action.
That TUC organised day-of-action is a response in part to the legislation being debated and voted on in parliament today to curb the right to strike in some public services.
Some schools will close for the day. Others will only be able to offer limited and sub-standard tuition.
This is quite a cost, both to students nearing exams and parents needing to go to work.
There will also be the difficult issue for heads of whether they ask teachers belonging to other unions to cross picket lines (and whether the heads cross picket lines).
The question which the prime minister and his government needs to reflect on, and has failed to do in any way that has been expressed coherently, is why so many workers in essential public services feel utterly alienated from them.
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