But, of course, the question of what - and how - young children should be taught has been regarded as extremely important since at least the time of Plato. Earlier this century, progressive education thinkers railed against the practice of making infants sit at rows of desks as if they were junior accounts clerks (Maria Montessori once likened young schoolchildren to “butterflies mounted on pinsIfastened each to his place”).

But as the pressure for even the youngest children to achieve certain targets has intensified, such “sentimental” views have been heard less often.

The sudden, massive transfer of four-year-olds from playgroups to schools that the ill-conceived nursery voucher scheme provoked has, however, rekindled the debate over the most appropriate education for infants. A recent Channel 4 Dispatches programme suggested that children in Hungary, Switzerland, Belgium and Germany made greater educational progress because they were not introduced to a formal curriculum until the age of six. But it is improbable that one television programme could have prompted this week’s statements by Estelle Morris and Margaret Hodge.

The Government has appeared uneasy about the number of four-year-olds in reception classes since at least the end of last year. It is therefore more likely that it is the arguments of the early-years lobby that have influenced politicians’ thinking. The report that the Early Years Curriculum Group published last October proposed that three to six should be designated as the nursery years. It also recommended that all four-year-olds should be taken out of reception classes, and that baseline testing should be postponed until the year in which a child becomes six. The group’s rationale is that three to six-year-olds are in a different developmental stage from older children. As Wendy Scott, chairwoman of the British Association for Early Childhood Education, has said: “We now have the scientific evidence from brain studies and child development work, to know that three to six-year-olds learn by doing.”

The argument is persuasive, particularly as the campaigners insist it is possible to be child-centred without being soft-centred - as in the rigorous and methodical curriculum followed by French nursery schools. Margaret Hodge’s assertion that a heavy emphasis on the 3Rs at too young an age can lead to disaffection, especially of young boys, is also supported by research in the United States. But, as ever, the truth is more complicated than either the Dispatches programme or the MPs suggest. The achievements of Flemish Belgian children may have more to do with the country’s excellent pupil-teacher ratios than their late start. Equally, Switzerland’s success may well be related to the fact that Swiss teachers are among the best paid in the world.

It is true that some four-year-olds are not mature enough for reception classes, but it is debatable whether most five-year-olds are too young to follow the national curriculum. On the contrary, many teachers believe that it provides Year 1 pupils with a range of stimulating “tasters” and encourages them to produce impressive work.

No doubt a better curriculum could be devised, but it is hard to believe that a totally new approach is needed - refreshing as it is to hear “child-centred” education referred to in a positive way. Today’s five-year-old “butterflies” may not fly freely but they are hardly pinned to their desks.