Q&A: Why are lessons being cut?

Hundreds of children are being sent home from a school in Croydon after the head teacher said he could not afford to pay supply teachers. How did this funding crisis come about? Will it mean more schools doing the same?

What sums of money are involved?

Head teachers in Croydon said earlier this year that they needed an extra £10m to ensure their budgets were not cut severely. Otherwise, they warned, class sizes could rise by a quarter and around 100 staff could lose their jobs.

Edenham High School, in Croydon, has forecast a deficit for the year of £220,000.

Who is to blame for the shortfall?

Nationally, the government and local authorities have been arguing over a "missing" £500m, which schools have not received. The government blamed councils for holding back the money. The councils claimed they had not received it in the first place.

Head teachers' budgets have been hit by increases in pension payments for staff, National Insurance contributions, pay rises and changes to working practices.

But last week, the government freed up cash put aside for building repair costs to be used for the day-to-day running of schools, including staffing.

Some schools said this was a useful freeing-up of resources. Others, which had already allocated their repairs budgets, said it would not be effective in preventing staff and other cutbacks.

In Croydon, Education Secretary Charles Clarke said earlier this year that the council had "failed to pass on" its share of a central government increase in school finances "by a significant amount".

In February, he used new powers to compel the council to put an extra £3m into schools. This, he said, would allow 92% of the increases given by central government to reach head teachers.

Why, then, is one school still having to send 720 pupils home early?

Jonathan Parker, head teacher at Edenham High, says funding problems are so severe he cannot afford to pay for supply teachers cover for sick staff. Last year this cost £65,000.

Mr Parker said the freeing up of repairs cash would provide £90,000. This would still leave the school with a deficit of £130,000, meaning there would still not be enough money to pay supply teachers.

Is this action a sign of things to come?

Mr Parker estimates the sending home of pupils may have to be repeated once a month.

Head teachers' leaders are also warning a similar situation may develop elsewhere, with some schools owing £200,000.

The National Association of Head Teachers has warned of a £2.5bn "black hole" in budgets over the next two years, raising fears of more children missing lessons.

In Croydon itself, heads have said a four-day week may be necessary to ensure budgets are balanced.

But the Department for Education and Skills insists Edenham High School is an exceptional case and is demanding an explanation from Mr Parker.