By Gary Eason
Education editor, BBC News website, at the NAHT conference
A primary school head teacher has said he will break the law because he cannot implement the deal on reducing teacher workloads in England and Wales.
Chris Williams said he would be forced to break the law
Chris Williams, head of a school in south Gloucestershire, said he was not prepared to go into deficit to fund the 10% time out of lessons for teachers.
He was backing a resolution at the National Association of Head Teachers conference calling for extra funding.
NAHT leader David Hart said the problem might force schools to close early.
Mr Williams' school has just 84 pupils in three mixed-age classes.
He said his staff had agreed they should manage this by having two adults per lesson - a teacher and a teaching assistant.
This meant there was no money left to cover for teachers to have half a day each week out of the classroom for planning, preparation and assessment - so-called PPA time - which is their legal entitlement from September.
So to provide it he would need the equivalent of another one third of a teacher - and he did not have the funding for that.
"I'm not prepared to see my school sink into deficit," he told the conference, being held in Telford, Shropshire.
"Therefore I will not be implementing PPA: my staff support me, my governors support me, my parents support me.
"But I will break the law," he said. "Help me please."
The conference heard complaints about lack of adequate funding from a string of head teachers, mostly though not entirely in primary schools - in England and in Wales.
Even many of those who said they had already implemented the agreement said they did not believe they could sustain it into the future - and that children's education would suffer.
Manchester delegate Brian Tetlow said: "The bottom line has to be high quality teaching cover - not a hotch potch of activities delivered by well-meaning volunteers."
Dot Lenton from Norfolk said: "The government must realise that to continue to raise standards we need to have paid professionals in our classrooms."
General secretary David Hart has said he believes thousands of schools will manage the change, but that a group would have trouble doing so.
David Hart foresees trouble implementing the workload deal
"I have spoken to head teachers all around the country in the last few weeks and some are talking actively about sending the children home at lunchtime on a Friday," he told BBC News.
Unions representing classroom teachers are insisting their members must get their entitlement, and are threatening legal action.
The NASUWT has been the most vociferous in criticising head teachers who say they cannot afford to implement the agreement.
It agrees with the government that the funding is available in schools' budgets.
But at a special meeting in March, the heads' association voted to pull out of the agreement.
The conference on Saturday urged a "more proactive" media campaign to explain the reasons behind this.
Catriona Williamson from the association's East Riding of Yorkshire branch stressed that the agreement applied to heads too - she should get 50% non-teaching time for her leadership duties.
It was about all staff having a better work-life balance and she could understand teachers worrying that it might not happen.
"We are not dinosaurs resisting change, we are not ostriches with our heads in the sand," she said.
"We want workforce reform - but we can't do it on a shoestring."
She rejected claims that some schools were "hoarding" money.
A survey of more than 70 in her areas had indicated that half were using financial reserves to make the agreement work.
Three were in deficit and only 22 could implement the agreement from their current budget.
"So next year we won't be hoarding - we will be seeing red," she said.