By Alison Smith
BBC News education reporter, at the ATL conference
Schools say funding will not meet demand for sixth form places
A funding error which could lead to cuts in sixth form budgets from September has left schools and colleges in England considering legal action.
The Learning and Skills Council (LSC), which allocates funds, miscalculated the number of students staying on.
As a result, it last month told schools that budget allocations made before funding was assured would have to be cut - some schools claim by up to 6%.
The government says it will try to find funds to honour the LSC's promises.
The situation in England is nothing like as bad as that in Wales.
There, a decision by the assembly government to cut sixth form budgets has been described by unions as "disastrous" and has prompted public protests.
The LSC had prematurely written to schools based on money not yet assured. Then, in March, it had to write to schools explaining the budget cuts.
Robin Bevan, head of Southend High School for Boys, in Essex, said he stood to lose £80,000.
It was not until 20 March that he received a letter informing him that his sixth form budget had been cut - by 6%, he calculates.
"Their letter was in edu-speak," he said.
"Buried away on page 13 was the answer to what had happened to our money.
"We're seriously considering all possible ways we can secure a positive outcome. That would include publicity, and possibly court action in collaboration with other schools.
He said the LSC "should have alerted the DCSF earlier that numbers were much higher than expected".
He sent the LSC his estimate of sixth form numbers in January.
At this point, he says, the LSC should have alerted ministers that numbers were above what was expected.
Although he has no intention of cutting courses or resources this year, he warned about future provision if funding problems are not ironed out.
"Minority subjects would be cut - subjects that typically get small numbers of students," he said.
"That would mean consequent reductions in facilities and staff."
That might mean typically French, German, and further maths, he added.
About £30,000 of his budget for "transitional protection" was being cut, he said.
This compensates his school because sixth-formers are now only funded to do up to four A-levels, but many of his pupils do five.
Other schools in Essex had been affected in the same way, he said.
He said sixth forms like his, where students tend to take a lot of A-levels, would be hardest hit.
The government has said it is trying to find the money to ensure all students' courses can be funded in the forthcoming Budget.
A spokesperson for the Department for Children, Schools and Families denied that 50,000 students might not be funded.
"As ministers have made clear, we are seeing an even greater surge in demand for places than we have budgeted for.
"We are still working across government on the extra financial support we need to provide for the new learners that are coming forward.
"The LSC will write again to schools and colleges at the end of this month.
On 3 April, once the errors had come to light, Schools Minister Jim Knight said that the increase in students staying on was "clearly related to the current economic climate".
He said better results and courses available had led to the increase.
Dr John Dunford, general secretary of the Association of School and College Leaders, sounded a cautionary note: "If the situation remains it will be a massive problem for schools.
"It couldn't have been handled more badly.
"But at the end of the day I'm confident there will be a solution and this will have turned out to be an unnecessary panic."
The Learning and Skills Council declined to comment.