Is there an ideal size for a school? That depends on who you are. There are few hard facts about how school size affects performance, but no shortage of assumptions. Parents think that small is best, at least at primary level, and ministers are said to be considering breaking up so-called large and unwieldy secondary schools into smaller units.

But politicians and local authority administrators have to keep an eye on budgets, and small is expensive. Many local education authorities think that primary schools of under 50 pupils are not viable.

The small secondary school is even less popular with the accountants, but the case for the big school is rarely put in financial terms. Instead it is argued that secondaries with fewer than 600 pupils struggle to offer a balanced curriculum.

“Nonsense,” says Keith Balich. “Everyone in the upper school here is taught by specialists.”

Mr Balich is head of the Aveland school in Sleaford, Lincolnshire, a county with more than its share of very small secondaries. Closing small schools isn’t an easy option in this county because of the huge distances that children would have to travel.

And the bean counters’ assumptions about size and viability appear to have been borne out here: several of the county’s small secondaries have been in special measures. Aveland was very nearly one of them.

“There were 213 on roll when I arrived,” recalls Balich, but he never accepted the view that small inevitably meant less. Aveland is now full, with 417 on roll, within Mr Balich’s ideal secondary size of between 400 and 600.

Parents pay for buses to ensure that their children can get to the school.

Lincolnshire has the 11-plus, but many local parents, including Mr Balich, chose Aveland even though their children passed the test and could have gone to a local grammar school.

“We had to attract those pupils. We had to make the place an attractive proposition,” he says.

To achieve that goal he invested in curriculum and IT, and made himself available to pupils and parents.

The school now prides itself on what it has to offer in music and dance. It employs a professional dance teacher and runs a dance festival. There are out-of-school opportunities for media studies, music and dance. Around 160 children take advantage of peripatetic music tuition, paid for by parents.

As for IT provision, it wasn’t easy. In his first year Keith Balich oversaw what he describes as a Disney budget, so called because he was making it up as he went along. Now the budget is under control and Aveland has 200 PCs as well as staff laptops.

Then there’s his own presence. “I can walk around this school on any day and be greeted by the children. I think that’s good and the parents think so too,” he says.

“When parents contact the school they know they will get me and that I will do something about their worries.”

The individual approach is one of the things that Tim Benson misses at his school in London’s East End.

“There are times when I feel frustrated that I can’t say hello to everyone every day,” he admits.

Mr Benson is head of the Nelson school in Newham, one of the largest primaries in the country with 865 on roll.

“We can’t get everyone into one hall. If we want to get the whole school together we have to do it outside, and we have only done that about twice in the past 14 years,” he says.

But asked to balance the pros and cons of large and small schools, Mr Benson comes firmly down on the side of the bigger establishment.

“I feel in awe of primary head colleagues who run small village schools,” he says. “I can’t imagine how they cover the curriculum.”

And what about the job of running the school?

“I’ve been head of three schools - first with 250 kids, then 500, now almost 900. I actually feel that my job has got easier over that period,” he says. ” In my first school I was doing an enormous amount of admin work.

Here I have an admin team of five.”

Mr Benson has a deputy and two assistant heads, and the school employs 90 staff including many specialists. That’s another advantage of size, he says: he can employ support staff for his special needs children. Between them his staff can muster more than 20 languages, a huge asset in a school with so many refugee and ethnic-minority children.

Dealing with the size of the school is a key issue for Nelson’s teachers.

The emphasis is on manageable groups. Playtimes and lunchtimes are separate, as is the accommodation for the nursery and foundation stage.

Nelson’s Victorian building may not be in the best condition, but its three floors and big rooms make it easy to offer children a manageable experience. When he arrived at the school in the 1990s, Mr Benson stuck with the long-standing practice of using the building’s three floors to run what are effectively three mini-schools.

“We have 240 children on each floor. Each one is equivalent to an average primary school,” he says.

Assemblies take place in the large, airy halls that are the central feature of each floor. Teachers work in floor teams with a head of phase, who in many ways is the head for each team. Curriculum co-ordinators for maths and English have whole-school responsibilities, but there are shadow co-ordinators on each floor.

Parents don’t appear to be unduly bothered about the school’s size, largely because of the three-floor system.

“He’s settled in fine,” says Diana Bigg about her son Ben, who’s five.

“They don’t feel part of a huge school of 900 children. All they think about is their floor.

“I wouldn’t want my child to go to a school with only 25 kids because I think that it reduces the chances for further learning. In a small school, if you have a bad experience or you don’t get on as well, you are stuck with it.”

That’s not a view shared by the National Association for Small Schools. It recently welcomed an Office for Standards in Education report which said that pupils in schools with fewer than 50 pupils were more likely to behave and achieve well.

“One explanation for the success of very small schools is that they are closer to the natural model of education within the family, with older and younger pupils working together,” NASS national co-ordinator Mervyn Benford argues.

It’s an issue that Mr Benson is aware of at Nelson, where opportunities are created for children to move between floors so that they can see the work of their older and younger peers.

“We found that was quite important to us to raise our standards. And the older children can set such a good example to the younger ones,” says Mr Benson.

He considers the ideal size is probably about 500, but says it isn’t the critical issue. “The key is whether the school works, not how big it is,” he says.

This may be a purely academic debate. In most places, the size of a school is driven as much by land availability and demand for places as it is by theoretical considerations. And Mr Benson argues that the near future will probably see completely different kinds of school organisation.

“The whole way we learn will transform over the next 10 to 15 years.

Looking into the future, we ought to be thinking about schools without walls,” he says.

But the last word ought to go to Mr Balich, whose elder daughter left her larger secondary school at 16 to go to the local further education college.

Her teachers were horrified.

“They said, ‘you need to stay. You are a bright child’,” recalled Mr Balich. “But she said ‘I’ve been here five years and that’s the first time you have told me that’.”