Dozens of teachers are to stage a series of one-day strikes in support of a colleague who was sacked for wearing trainers and tracksuit bottoms to school.
Staff from St Paul's Way Community School in Tower Hamlets, east London, are planning five walk-outs beginning next week in protest at the dismissal of Adrian Swain.
Mr Swain achieved national prominence in December when he was fired for persistently failing to follow the head's instructions to dress more professionally. His appeal was rejected last week.
Members of the NUT have voted overwhelmingly in favour of striking. The vote was nine to one on a turnout of about 75 per cent.
The first walk-out is planned for next Thursday, with four others to follow within a fortnight, unless Mr Swain is reinstated.
With almost 60 members in St Paul's Way, the union expects the school will struggle to open.
"I have always had support from other teachers in the school," Mr Swain said. "Of course it would be in everyone's interest if this could be sorted out sensibly and I was given my job back. I believe I have been victimised because I was the branch secretary for my union.
"I have never believed that I was sacked for what I was wearing on my feet."
An emergency meeting between the NUT and Tower Hamlets council has been scheduled for next Tuesday, but unless the situation can be resolved, the strike action will go ahead.
Mr Swain, who has been a teacher for 35 years, was fired for failing to comply with a "reasonable management instruction" when a new dress code was introduced by the school's former headteacher.
Mr Swain complained that the code was poorly defined and had been introduced "arbitrarily" without any consultation with staff. He told The TES in December that it was a "bully's charter".
Following the appointment of a new headteacher, a consultation on the dress code has now been completed.
Mr Swain told his appeal hearing that he would be willing to follow the rule despite not agreeing with dress codes.
"What I wore didn't affect any other headteacher I have worked for in the past 35 years," he said.
He said it was unlikely he would be able to get another job in teaching after his sacking.
A spokesman for Tower Hamlets Council said: "Should any strike go ahead, the local authority will work closely with the school to minimise the impact on pupils."
Meanwhile, teaching unions in Leicester are threatening industrial action at Fullhurst Community College because of "intolerable working conditions", including allegations that staff feel under threat of assault.
There are also complaints that there is no suitable staffroom, teachers have to share toilets with pupils and that some classrooms have no electricity except for lighting.
Teacher unions are awaiting a report from the local authority before deciding whether to issue a strike ballot.
What not to wear Other shoes to avoid
Other shoes to avoid