For parents whose experience of school was back in the Eighties or earlier, the lack of tables and chairs at Sue Walker’s school can come as a surprise. She admits that it prompts some to wonder if there is any point in sending their child to school at all: “We have to win them over and convince them that it works.”

Mrs Walker, head of Shears Green Infant School in Gravesend, Kent, believes that allowing four-year-olds to wander the room at will, spend their time in the sandpit, or decide whether to make a space rocket or a jungle, is the best way to ease their transition from pre-school to the classroom.

But many schools eschew this play-based approach and offer a more formal education at this stage. At five years old (four in Northern Ireland), UK children are already some of the earliest starters in Europe. In practice, many schools admit children to reception at the beginning of the year in which they turn four. According to the latest figures from the Department for Children, Schools and Families, 99 per cent of four-year-olds in England are in some sort of education provision, with 61 per cent in infant schools. But is this too early to be exposed to the strictures of timetables and lesson plans?

This trend towards starting at four will be enshrined in law if the Government accepts the conclusions of Sir Jim Rose’s interim report into the primary curriculum. Published late last year, with the final version due out in the spring, it recommends that children should start reception in the September after their fourth birthday, standardising what is already common practice in many areas. If this is approved, it will come into force from 2011.

But disquiet about this proposal is growing. Even before Sir Jim’s report was published there were fears that children were starting education too soon. The Government’s Early Years Education Advisory Group has expressed “grave reservations” about the curriculum for four and five-year-olds, and advocated putting off formal education until children reach the age of six.

David Whitebread, a former primary teacher and now an early years specialist at Cambridge University, believes the review’s recommendation is going in the wrong direction. He would like to see formal schooling delayed until six, rather than brought forward to four. “There is no evidence that starting earlier makes any difference, and quite a lot of evidence to suggest that shortening the time a child spends in high- quality informal education is damaging,” he says.

“Pushing children into reading and writing before they are ready can undermine their confidence, creating problems that could last throughout their schooldays.”

While many reception teachers may aim to provide a play-based approach, Dr Whitebread says the lack of specialist training and the pressure to reach curriculum goals means play is often squeezed out. “In practice, they tend to start formal teaching of phonics and numbers,” he says.

Critics of the UK’s early starting age frequently point to Finland, where children tend to outperform their UK counterparts - coming top in the latest Programme for International Student Assessment tests, for example - although they do not start formal schooling until seven. But this is not the whole story; most Finnish children attend a pre-school year, which incorporates elements of formal education.

Caroline Sharp, principal research officer at the National Foundation for Educational Research, says evidence on the link between achievement and school starting age is far from conclusive. “It is difficult to say definitively what the best age to start school is,” she says.

It may be a crucial - and controversial - issue, but setting the compulsory school starting age at five was not based on educational criteria at all. Instead, it was introduced with little discussion in the Education Act of 1870. During what little debate there was, arguments in favour included the need to protect children from exploitation and unhealthy conditions on the streets, and that a younger starting age would allow for an earlier leaving age, which would benefit employers.

Subsequent changes have extended the time children spend in compulsory education, from the six years of the 1870s to 11 now. Changes brought in last September require all children to remain in education or training until 17, although this only applies to children now in Year 7 or below, and does not necessarily mean they will stay in school.

At the other end of the age range, there has been rapid expansion in the number of reception classes. The 1988 Education Act created a market where schools compete to attract parents. The prospect of free full-time childcare provision, and securing a primary place into the bargain, is too tempting for many parents to resist. The result is that most children can expect to spend 13 years in education or training.

But research suggests that this early start makes little difference. “It gives them a short-term advantage, as you might expect,” says Ms Sharp. “But having children start full-time education earlier does not necessarily give them a long-term advantage.”

She warns against setting too much store by international comparisons. While other countries hold off introducing formal concepts until a later stage, school starting age is not the only variable. The quality and reach of pre-school provision, staff qualifications and training, economic advantage, parental support and the status of education - among other factors - all have a part to play.

The evidence may not show that starting school at five gives children an advantage, but nor does it suggest that six is best either, Ms Sharp adds.

It is not so much the age as the curriculum and the environment that is crucial. Providing play-based learning with well-qualified staff in a suitable building, with ready access to outdoor space, is the ideal. While this can be easier in an early years setting than a school, Ms Sharp says it is by no means impossible.

“It can be the difference between a setting that is much more play orientated and where academic demands aren’t being made, and a school system where the children have to sit still and listen to what the teacher is saying,” she says.

“The important thing is the age, plus what they’re getting. The last thing we want is for children to be bored with learning or to think of themselves as failures at such an early age. It is about making the setting ready for the children, rather than trying to make children ready for school.”

This is where Mrs Walker’s approach comes in. She is aware of the difficulties children can experience when moving from pre-school to reception. While each reception class at Shears Green has a teacher and two teaching assistants, the ratio is still not as favourable as the one adult to four or five children in most pre-school settings.

So at Shears Green there is an emphasis on crayons rather than pencils. “Everything we do is play-based and a lot of it is child initiated,” says Mrs Walker. “It can hurt to hold a pencil, and if you put a pencil in a small boy’s hand, it can put them off.”

This determination to keep play at the heart of the reception year means the school has moved some curriculum areas, such as knowledge of the world, from the foundation stage to Years 1 and 2.

The issue of school starting age is particularly acute for summer-born children. A study by the Institute for Fiscal Studies found that summer- borns scored an average of one level lower on tests at seven years old.

Research by academics at Oxford, London and Nottingham universities found that summer-born children were more likely to be identified with special needs by the age of 11, although the difference had disappeared by 16, suggesting that immaturity was being mistaken for learning difficulties.

These findings were reinforced by a Cambridge University study, published last month, that confirms summer-borns perform less well than their older classmates, with the effect most pronounced during infant and primary school. The gap narrows, but is still significant, at GCSE and A-level, and it is still in evidence at the end of higher education.

The researchers found that a common start date, as advocated by Sir Jim, does not address the disadvantage, but it is greatly reduced in countries where formal education begins later.

While most local authorities used to run two entry dates, with summer-born children able to start school in January, many have now switched to a single September start. The consequence of this is that some children now go into school shortly after their fourth birthday, and the starting age has crept down by default.

“That is neither necessary nor is it acceptable,” says Margaret Morrissey, of the lobby group Parents Outloud. She believes that some parents enrol their children in reception as a way of securing a place in a school, but argues that the problem would be eased by returning to a two-term entry: “If you’re four in April but don’t start school until January, that is another four months - and that makes a big difference.”

Concerns over the direction of early years education prompted a group of academics and early years specialists to launch Open EYE (Early Years Education) in November 2007, in opposition to what they see as an overly- prescriptive and potentially harmful curriculum. Last month, the campaign published its response to Sir Jim’s report, arguing that there is no reliable evidence to support a single entry point into reception after a child’s fourth birthday.

Richard House, founder of Open EYE and a lecturer at Roehampton University, says: “There has been a kind of surreptitious lowering of the school entry age without any public debate, and this is an attempt to enshrine that in law. We think it is moving in the wrong direction.”

Freda Carlsson agrees. She turned down the reception place offered to her daughter just two months after she turned four in July 2006. “I felt she wasn’t ready, socially or emotionally,” she says.

Mrs Carlsson, originally from South Africa and now living in North Yorkshire, says if she had stayed in her native country, her daughter, now six, would only just have started school in January. But if she had taken up that reception place, she would now be in her third year of school.

Eventually Mrs Carlsson found a school willing to take her daughter one day a week from the February, only going full-time for the last month of the school year. “Academically she was probably fine, but she didn’t want to socialise and sit and do things,” she says.

“She missed almost the whole of the reception year, but you couldn’t tell now. I think she has benefited because by the time she started school she really wanted to go and now she jumps out of the car and sprints in.”

Although there is no legal requirement to send children to school until the term after their fifth birthday, Mrs Carlsson says she felt pressured by the local authority and the original school to send her earlier.

“There is an implicit assumption that if your child doesn’t start at four, he or she will fall behind.”

It is not just parents who are uneasy about the starting age. A TES survey of 600 heads and classroom teachers just over two years ago found fewer than one in five were in favour of children starting school at four or younger, while 40 per cent wanted formal education to be delayed until six.

The following year, at its annual conference, Voice, the teachers’ union, echoed this support. Philip Parkin, its general secretary, says that five is too young to begin formal learning for many children: “Often they have not acquired the social skills they need.”

Mr Parkin acknowledges that delaying formal schooling would require additional resources, but argues that some are already available in the form of surplus capacity in schools.

Mr House of Open EYE says that however much reception classes try to concentrate on play, this is undermined by the emphasis on directed play in the Early Years Foundation Stage.

“As soon as you get learning outcomes and a grown ups deciding what a child should be learning, that is not play by any meaningful definition,” he says.

“As soon as children go into a reception class, there is a sense that this is not like home, it is about learning instead.”

While some five-year-olds may cope well in school, it does not suit every child, says Neil Leitch, of the Pre-School Learning Alliance: “It is not an exact science, and it is very much dependant on the use of appropriate pedagogical approaches in meeting the needs of a child, particularly their social and emotional needs.”

He suggests the development gap between a four and a five-year-old is similar to that between an 11 and a 14-year-old. Despite the evidence that summer-borns are at a disadvantage, he acknowledges that the effort required to tackle this may prove overwhelming.

When so much is invested in the existing system, he is sceptical that any meaningful change is looming. “We know the problem is there, but somehow we come back to the same old thing,” Mr Leitch says.

We may have arrived at a school starting age of four by default, but enrolling children in reception at the earliest opportunity is now backed by the weight of custom and practice. It will soon become clear if Sir Jim has resisted the wave of protest against his proposal to make this a legal requirement, but without conclusive evidence either way it seems unlikely the tide will be reversed any time soon.

STARTING AGES IN EUROPE

• 4 - Northern Ireland
• 5 - England, Malta, Netherlands, Scotland and Wales
• 6 - Austria, Belgium, Cyprus, Czech Republic, France, Germany, Greece, Hungary, Iceland, Republic of Ireland, Liechtenstein, Lithuania, Luxembourg, Norway, Portugal, Slovakia, Slovenia and Spain
• 7 - Bulgaria, Estonia, Denmark, Finland, Latvia, Poland, Romania and Sweden

• Source: National Foundation for Educational Research.