"Children are failing to develop normally because they are denied access to imaginative, active games by misguided parents", says Sue Palmer.
It's an overnight bestseller: a book that reminds boys of the age-old joys of conkers, go-karts, water bombs and skimming stones. The Dangerous Book for Boys, by Conn and Hal Iggulden, is a treasure trove of ancient boyish lore that will gladden the heart of any young male.
But it's parents who really need this sort of prompting. Children today are suffering from a severe shortage of something as necessary to growing bodies and brains as oxygen itself: outdoor, loosely supervised play.
Until quite recently, children everywhere went out to play. They played at building and making things (dens, dams, forts), make-believe and role-play (pirates, show-jumping, cowboys), and at running, jumping or climbing trees in the garden, park or local "wild" places. Older children would disappear from home for hours on end, for kick-arounds on the local playing field, or to explore the neighbourhood on their bikes.
It wasn't just infant bodies that grew fit and strong through play; it was brains as well. Scientists studying the development of the human brain agree with experts in education: play is the natural basis of human learning. When researchers at London University found recently that today's 11-year-olds trail two to three years behind their counterparts in 1990, they put the change down to the loss of play.
In the past 15 to 20 year, there have been immense changes in children's lifestyle. A huge increase in seductive, indoor, screen-based entertainment has produced the most inactive generation in history. Scottish researchers found that today's two-year-olds are as sedentary as office workers and that, once acquired, the couch-potato lifestyle is difficult to change.
For many children, "play" now means sitting down at a PlayStation. Games are something they buy for their Game Boy. But even computer games are more active than the mindless grazing of children who spend four or more hours a day staring at a television screen.
There is a growing body of research showing that screen-based second-hand experiences are no substitute for genuine engagement with the real world. The neural networks in which children's future learning is embedded can only be forged through real experiences anre real-life interaction.
Television compounds the play problem by affecting parents' attitudes, making them damagingly overprotective. Although life for most of us today is safer than it has ever been, we grow ever more fearful of letting our children out of the house.
There are real dangers, of course, from road traffic but, with community effort, these can usually be overcome. The truly crippling fear - that prevents us taking action - is deeper and largely irrational: the fear that a stranger will spirit our child away. For while child abduction and murder is mercifully as rare as it has ever been, our awareness of it is massively magnified.
News of every vile assault on children is now immediately and attitudes, graphically transmitted into our living rooms, hijacking the emotional centres of the brain and interfering with logical thought. When every parent can instantly summon up the tragic images of Jamie Bulger, Sarah Payne, or Holly and Jessica smiling for that last photograph, the natural instinct to protect their offspring turns rapidly into crippling paranoia.
Play - unstructured, free-range, loosely supervised play - is the birthright of every child. For the next generation to grow up healthy, balanced and able to benefit from their education, we must ensure that children once again go out to play.