The palaeolithic era just about fits behind the church door. Inside a Brighton Methodist church hall, two children have decided to explore early history by rolling out a 20ft frieze, a timeline of our prehistoric past, along the corridor. The late palaeolithic gently buffets the door.

As they colour pictures of our early ancestors, teacher Deirdre Finnegan explains the Montessori approach to history.

“We want to get them thinking about the idea of service and community,” she says. “The nameless humans in these pictures created the wheel and fire.

They made a great contribution, so children start thinking, ‘what will my contribution be?’”

But it is the way the history rolls out along the corridor that tells a more pressing story for Brighton and Hove Montessori school. It is desperate for space.

The church hall stands across the road from headteacher Daisy Cockburn’s imposing Victorian home, where a door to the basement leads to the nursery section of the school she founded in 1985.

She cheerfully describes the scenes within as “organised chaos”. Montessori schools are supposed to look like this - groups of children making their own choices about what to learn and when to learn it.

Some paint while others listen to stories, or use pegboards to work out their times tables. One girl stands by the stairs “waiting for a friend”.

Ms Cockburn gently coaxes her to do something more productive.

Three four-year-olds are washing up with vigour at knee-high sinks.

Furniture in Montessori schools is all child-sized, and the schools are big on teaching children to wash and tidy up after themselves.

There are 75 children now, aged three to nine, and no room for more. But that may be about to change. With a pound;5 million grant from the Department for Education and Skills, Ms Cockburn plans to build the first purpose-built, state-funded Montessori school in the country.

It is several years now since education ministers declared their aspiration to see more diversity in schools. Four Muslim and two Sikh schools have since joined Christian and Jewish schools in the state sector. A Hindu school is planned in Harrow.

But for those offering alternative educational philosophies rather than faiths, the wait goes on. As Christopher Clouder, chair of the Steiner Waldorf Schools Fellowship, says: “It’s a lot more complex than we imagined.”

Voluntary-aided status seemed the most obvious route. Brighton Montessori is still pursuing it, but Steiner schools have all but abandoned that approach in favour of creating city academies, partly because of difficulties in reaching agreement with local authorities.

The decision on opening new state schools lies with local school organisation committees. If accepted, they must follow the national curriculum, set Sats, operate a lawful admissions system, and have a head and governing body. Teachers must have qualified teacher status and be paid in line with national terms and conditions.

These conditions are relatively straightforward for minority faith schools, which follow a similar model to Christian schools with a high premium on traditional teaching. But they may be more challenging for those offering alternative education.

For Brighton Montessori, the change of status will mean a huge expansion. A school of 180 pupils is proposed to open in September 2006 on a new site and a pound;5m capital grant has already been secured from the Treasury.

The proposal is now out to consultation, but the biggest hurdle is setting an acceptable admissions policy.

Church schools can stipulate families follow their faith, but schools with a distinct educational philosophy can make no such demands.

Steve Whitehead, project assistant at the school, says: “If the Government is serious about diversity and parental choice, it is going to have to accommodate it.”

The answer, based on consultation with the DfES, could be a system of random selection that also ensures a wide geographical spread and gives priority to children with special needs and to siblings. It would also give priority to pupils who have attended the nursery.

The local education authority remains unhappy, arguing that the system may discriminate against poorer families who cannot afford to travel.

Arrangements if the school is oversubscribed are opaque, and there appears to be a mismatch between nursery and infant numbers. Officials also fear the school will take resources from other schools and may not even be financially viable.

Given those hurdles, questions of school leadership seem some way off but will have to be addressed. Staff will have to gain Qualified Teacher Status - Ms Cockburn believes they can qualify on the job - and undergo performance management. Ms Cockburn hopes to avoid a “culture of competitiveness” by involving Montessori Education UK, the national accreditation association.

Each class of 30 will cover three years - ages three to six, six to nine and nine to 11. Ms Cockburn believes the larger size will benefit the pupils. Montessori education, she says, depends on diversity and the interactions between children, “so you’re actually looking for more children, not fewer. You’ll have diversity of age, ability, background, personality and gender. They will be much more socially able.”

As for the national curriculum, she is not worried. Despite appearances, they cover the curriculum and more. In any event, “you become a Montessori school by delivering education in a Montessori style. It’s not what you learn but how you learn it”.

Children have informally taken Sats and done well. Ms Cockburn views the tests as diagnostic aids rather than an end in themselves. “We’ll just find our natural place in the league tables.”

There will be opportunities for collaboration. Ms Cockburn says she hopes her teachers will work with mainstream schools and the LEA. Similarly, a board of governors will bring in new ideas.

The school is already required to keep a raft of policies from health and safety to special needs. The nursery has been inspected by the Office for Standards in Education. Inspectors found a “very happy, stimulating and productive environment” where “most children are likely to achieve in the desirable learning outcomes (by age five) and some will progress further”.

Human Scale Education, the charity which promotes small-scale schools, recently saw one of its schools rejected for voluntary-aided status in Cumbria, but remains hopeful of success. Meetings with Education Secretary Charles Clarke had even produced a personal pledge of support. “You can’t get more than that,” says project leader Fiona Carnie.

The challenge for schools will be holding on to their principles, she believes, with the biggest difficulty being testing.

“The Government is becoming less prescriptive about the national curriculum, so teachers will have some leeway about what they teach. But they are not happy with the test-driven system.

“We would have to hold tests in a sensitive way. Luckily, if it’s a very small school, with fewer than 11 children in the cohort, we don’t by law have to publish the results in league tables.”

Schools would also have to get used to rules on how they spend their money, Ms Carnie said. “Independent schools have a big headache getting the money they need. In the state sector, they’ll have the money, but they’ll have less freedom on how to spend it.”

For Steiner-Waldorf schools, which have no head (staff take it in turns) the upheaval will be greater. Mr Clouder says some in the movement fear the special nature of the schools could be watered down. But he believes they have little choice.

“Survival is more and more difficult,” he says. “But in countries that have state funding, such as Sweden and Finland, we’ve seen Waldorf education flourish.”

Pedagogical freedom is a concern, but Mr Clouder says the Government has given assurances the schools’ integrity will be preserved. There are worries about testing. And the schools will have to appoint a permanent head.

“These are certainly not insurmountable problems. Our schools would probably benefit from a more rigorous approach to responsibility and assessment,” Mr Clouder says.

He adds that such a post would not interfere with what happens in classrooms. Ofsted may find that approach interesting.

www.brighton-montessori.org.ukwww.steinerwaldorf.org.ukwww.hse.org.