It is the ultimate final resort for heads dealing with their most badly behaved pupils. Exclusion from school has always been an educational full stop, punishment through banishment, designed to send a clear message to the errant child. But now this age-old principle of exile from school in retaliation for unacceptable conduct is being reversed.
For while education secretary Michael Gove and his ministers might look to the past for so many of their school and curriculum reforms, when it comes to exclusion they are trying a bold new approach.
This September they will start a daring experiment with national behaviour policy. In future, heads will retain financial and moral responsibility for the children they exclude.
School leaders will have to find and pay for alternative places for students they get rid of - either in pupil referral units (PRUs) or in alternative provision - courses run by charities or companies.
In addition, the child's subsequent exam results will still count towards the school's place in performance league tables - creating a "no excuses" culture for heads.
At present, responsibility for their schooling at the point of exclusion is handed to the local authority, which most often uses PRUs as a short or long-term solution. Many critics argue that this leaves the young person floundering, with no one taking a long-term interest in their education.
The change of policy, designed to prevent this situation, was first mooted in last year's schools white paper and will be tested in a three-year pilot. Around 12 local authorities have signed up to take part, and eight more are still coming to a final decision. All those involved will hand over their exclusion budget to schools. A total of 50 local authorities expressed an interest.
The thinking behind these reforms has been praised by academics and campaigners. But some school leaders are concerned about the impact the changes will have on their budgets if, despite getting the council funding, they end up having to contribute towards expensive alternative provision. They warn that this could leave them having to choose between excluding badly behaved pupils or employing teachers which would, in effect, stop them being able to sever links with the worst-behaved children.
"If it's a serious event we often have no choice but to exclude, and if this is for a group of children this could really have an impact upon us," says Peter Campling, head of Deptford Green School in Lewisham, London.
"Ten years ago I excluded nine children after a particular incident - they made up almost 10 per cent of my year group. I would not want to be held to account for them.
"I understand the Government wants a system where schools can't just offload difficult children, but this is just crazy. It beggars belief that we could be paying for children's alternative provision for five years after we've excluded them.
"I don't know any headteacher who excludes in any other situation apart from a last resort, because they see this as a failure by the school. The Government needs to put trust in heads over this issue."
Heads may insist exclusion is always a last resort, but the Department for Education says the changes will stop any "abuse" and "create a strong incentive for schools to avoid exclusion where possible, and ensure that where it does happen it is appropriate and pupils receive good alternative provision".
Shauneen Lambe, director of Just for Kids Law, a charity which provides support, advocacy and assistance for young people, says she still sees "shocking" abuses of the exclusion process.
"At one school teachers wanted to exclude a nine-year-old boy just because he told his teacher: 'I want to kill you.' The idea that a school might expel a child for that, just using words, is terrifying.
"Schools do provide a huge amount of support for children with statements, but for those without a statement this would be seen as taking valuable resources away from the other pupils in the class. I understand the problems teachers face, but they need to be helping children stay in mainstream school."
Sam Murray, head of policy and information for the Advisory Centre for Education, a charity which provides advice and information for parents, says she has found teachers too quick to exclude.
"Problems do get picked up, and schools try a range of things to help, but parents often say teachers move through these very quickly, and in a half-hearted way, before the pupil has had a chance to try them properly or be engaged with them, and then they are permanently excluded," she says.
"Perhaps knowing they will remain responsible for these children will mean teachers will put 110 per cent into making things work for them at the school."
The DfE will be watching closely to see, when given a free choice, which option schools choose as the best place to send their excluded children.
The use of permanent exclusions has been falling in recent years, and the previous Labour government put pressure on schools to use alternative solutions such as "managed moves" of children to other schools.
Some local authorities have already gone some way to introducing the changes Mr Gove wants by handing responsibility for PRUs and alternative provision to heads. The good news for him is that in these areas there has been an immediate positive impact.
Two pioneers, Cambridgeshire and Staffordshire county councils, have seen the number of exclusions fall dramatically. But schools have also used the changes as an option to spend less, which has not been good news for PRUs.
Cambridgeshire heads have sought to save money by buying fewer places in PRUs, and setting up their own internal inclusion centres to cater for children who need extra help. Heads follow protocols agreed with the council about the curriculum these pupils follow and the number of hours of education they are given.
The council employs support workers, who work in schools with children with extremely "complex" behaviour.
Jane Ryder-Richardson, the council's head of access, says the changes, made two years ago, have made schools more creative and inclusive.
"We thought there would be more interest in buying alternative provision than there has been. We've found schools have preferred to establish their own systems," she says.
"Before the changes there was a real push from schools to put children in alternative provision - because of the expense in budgetary terms this just wasn't making sense.
"The schools which have become academies are still working within the partnerships. If they pull out we will have to review the system, but we've not got to that point yet and everyone is keen to maintain the current working relationship."
The number of children in Cambridgeshire in alternative provision has fallen by 50 per cent.
Mark Patterson, principal of Chesterton Community College, in Cambridge, and chair of Cambridgeshire Secondary Heads, says generous funding is the reason for the success of the changes. He and five colleagues receive #163;900,000 a year to spend on alternative provision and PRUs.
"This amount of money is critical," he says. "It just wouldn't work if we were given, say, #163;7,000 a year - that's not enough. We are providing good-quality alternative provision, and we can use the money to make sure we can also provide for (pupils) within school. It's a win-win situation for everybody.
Mr Patterson says that before these changes, alternative provision in Cambridgeshire was "patchy".
"Now we can maintain the good, but we also have an influence over the satisfactory because the PRUs know we don't have to buy their places. This gives them an impetus to improve," he says. "We have insisted on a clear maximum number of children in PRUs to preserve their quality."
In Staffordshire, heads decide how the alternative provision budget is spent, but the money is still managed by the local authority. Schools are grouped into eight districts, or "inclusion partnerships", and each has links to at least one of the county's six PRUs.
The system was set up five years ago to improve the quality of alternative provision in the county, some of which, according to Alison Greenwood, education and inclusion partnership manager, "wasn't that good".
"Now we have a more consistent range of alternative provision which fits in better with what schools want," she says. "We've ended up using the same providers, but what they provide is different, more appropriate and better quality-assured because if it's not good, schools won't commission it.
"Schools now feel less disconnected, our exclusion rates are below the national average and exam results at our PRUs are three times the national average. At the same time schools work very hard not to exclude and most children in PRUs are dual-registered there and at their previous primary or secondary."
Ms Greenwood, who is on the steering group set up by the Government to oversee the exclusion pilot, says changes in Staffordshire have led to money being spent "more efficiently".
"We had a lot of children getting expensive tuition. Now I'm working with the same budget as five years ago, but we put it to better use through switching to different providers," she says.
"We had a cycle where, because local authorities had responsibility for exclusion, children ended up in expensive provision and they didn't get back into school. Now schools have taken collective responsibility."
Carl Parsons, visiting professor of social inclusion studies at Greenwich University, is also on the DfE steering group. He believes the changes to exclusion will get rid of a "layer of involvement" from local authorities that "hasn't worked well".
"Now, if heads are commissioning PRU places they will find it hard to look parents in the eye and say it's the best place for their child if they know it isn't," he says.
"But we have no idea of the effects of these reforms. Will excluded children lose fewer days of education? Will exclusions go up or will it act as a collective deterrent?
"I believe there should be no excuses from headteachers about why they have excluded. It's their job to sort these situations out rather than to drop children into the abyss."
Mr Gove and his civil servants certainly have serious issues to solve with their exclusion pilots, and they need to decide how the policy will work with falling school budgets.
The three-year trial might convert heads to the need to retain care for their most troublesome pupils, or it might end up proving their point that exclusion should mean exclusion for good.
Exclusions fall by nearly 20%
There were some 6,550 permanent exclusions from primary, secondary and special schools in 200809 - 0.09 per cent of all pupils in schools. This is a fall of 19.4 per cent on the previous year.
In 200809, the rate for boys was about 3.5 times higher than that for girls. Boys represented 78 per cent of the total number of permanent exclusions.
Pupils with SEN (with and without statements) are more than eight times more likely to be permanently excluded than those without special needs. In 200809, 24 in every 10,000 pupils with statements and 30 in every 10,000 pupils without statements were permanently excluded. This compares with three in every 10,000 pupils with no SEN.
Pupils eligible for free school meals (FSM) are around three times more likely to receive either a permanent or fixed-period exclusion than non-FSM pupils.
The most common reason for exclusion (permanent and fixed-period) was persistent disruptive behaviour. Some 29.6 per cent of permanent exclusions and 23.3 per cent of fixed-period exclusions were due to this.
A total of 11.1 per cent of permanent exclusions and 4.7 per cent of fixed-period exclusions were due to physical assault against an adult.