With research indicating that 80 per cent of a child's language development is embedded by the age of five, there is growing concern that many pupils' progress will be severely impeded by language delay in the early years.
"The evidence is anecdotal, rather than statistical, but the number of children with these sorts of problems definitely seems to be on the increase," says Gabriel Jones, who works as an under-fives adviser for several London boroughs.
Significantly, says Mrs Jones, not all of these children come from homes which fail to provide the kind of "stimulating parenting" that is so vital to language development. "The parents are usually trying their best but, for whatever reasons, the children don't seem to be making the connection between spoken words and their meanings," she says.
"I recently worked with a little girl in a playgroup in Ealing who had age-appropriate abilities in almost every area - except that she was using no spoken language at all. She came from a well-stimulated background, so it was a real mystery. "
Valerie Savage, an independent speech and language therapist who works with young children, believes a lack of age-appropriate comprehension skills is even more worrying than a delay in the development of expressive language.
"Some of the children I see have enough comprehension to get by at home. They can cope with the 'come heres' and 'sit downs'," she says, "but they struggle with the more varied and unpredictable demands of the unfamiliar school environment. Earlier this month I had a call from a nursery school teacher who was dealing with a boy who could not follow even the simplest of instructions."
The list of contributory factors cited by speech and language experts is invariably headed by the popular villains - TV, videos and computer games. London-based educational psychologist Peter Kendall believes the ever-increasing dependence on visual, rather than verbal stimuli is affecting us all: "People in general listen less attentively now than ten years ago, particularly kids. They use their imaginations much less when passively watching a video than when they are absorbing and responding to direct speech from a parent or sibling."
In such a climate, he says, it is even more important for parents to throw the ball back when they are talking with their child. "If a child says 'bus', you can say something like 'Yes, there's a big red bus'. That's a good way of adding variety to their language skills." Increased emphasis on rhymes and songs also enriches the home environment, he says.
Ms Savage wants to see an increase in the amount of cash directed towards identifying and helping children under five with speech and language delay.She says: "If groups of about six children could have a weekly two-hour session with a qualified speech and language therapist and a teacher, there would be a significant long-term benefit. You would also save money by reducing the number of children who receive statements of special needs once they start school."
Based on a logical, if far from obvious, comment from Mrs Jones, the Government's education advisers might also consider promoting a return to old-fashioned means of child transport.
"In the days when a mother pushed her child in a pram, they were face to face and she would be more likely to talk to the child, describing its surroundings," she says. "With pushchairs, the child is seeing without interpretation, which is much less helpful. "