A ‘on-off’ strike at a controversial free school was set to start yesterday (Wednesday) after talks with bosses broke down.

Teachers at Stem 6 Academy, in City Road, Finsbury, had voted to walk out last week over stingy “zero-hour” contracts, but at the last minute school chiefs and the National Union of Teachers (NUT) got round the table and avoided what would have been the first ever strike at a free school.

On Monday night parties were set to discuss “deplorable” working conditions staff say they were forced to sign, but the union say the academy’s top brass tried to cancelled the meeting and renege on an agreement to discuss terms.

Now teachers will picket tomorrow and Thursday as well as three days next week.

Ken Muller, assistant secretary of Islington NUT, said: “This game playing must stop if we are going to return to where we were after Stem 6 agreed last week to recognise the NUT and enter in to meaningful negotiations with us about teachers’ terms and conditions.

“The obvious reality is that teachers at the school are angry at the disgraceful way in which they are being treated and are prepared to take the action necessary to rectify the situation.

“It’s the students we feel sorry for - they are the ones who are going to suffer.”

Teachers claim they had to sign, on pain of legal consequences, contracts saying:

The school can lay them off without pay or cut their hours, with as much notice as they can reasonably give.

They can receive just three weeks’ sick pay a year.

They are only entitled to statutory maternity leave.

The NUT says these are far worse conditions than most Islington schools offer, but because Stem 6 is a free school, Islington Council has no say in how it is run.

John O’Shea, Principal STEM Academy Tech City, said: “I am deeply shocked the NUT has renewed its strike action, given that it has been made perfectly clear that the school’s Governing Body is willing to recognise the union and to enter into meaningful negotiations.

“Late last night, the union presented a draft agreement for us to sign, which, on legal advice, we have been told does not adequately apply to free schools such as STEM Academy. I have therefore asked for a suitable agreement to be sent as soon as possible for us to review – however, this has not been forthcoming.

“Instead of continuing with the process we had thought was in train, the NUT has instead chosen to take unnecessary, drastic action, to the detriment of our students above all else.”