In the 1930s a Scottish miner seeking work moved his family to the Kent coalfield. After settling them into a house in Betteshanger, he travelled back to Scotland and removed a door frame from their old house.

He carried it back to Kent and carefully built it into one of the doors there. Why? Because this precious scrap of wood was covered in the pencil marks that he and

his wife had made as they measured the growth of their children. He could not bear to part with this tangible record of their growth and health.

Parents have always wanted to track their children's progress, and until about 30 years ago had little difficulty.

Schools would measure children's weight and height at least once a year and include it in their reports. While not as much fun as pencil marks on a door frame, they were probably more accurate. Somehow, like much in

the education system, this excellent practice petered out. Now that we have an obesity epidemic upon us, the Department of Health is scrambling to reinvent the wheel, though it is entrusting primary care trusts rather than schools with the task.

And what an unholy mess it is making of it. Parents were given the right to opt out, so the first year of measurement (2006/2007) caught only 50 per cent of 6 and 11-year-olds. As many of those who opted out were fatter children, the data were effectively worthless as an index of obesity.

Last year the department set a target of measuring 80 per cent of 6 and 11-year-olds, and met it. But why not 100 per cent? So obsessed are officials with avoiding any hint of stigma that they are missing a chance to do the job properly.

Even stranger is the attitude the department takes to the information once it is gathered. It first decided that it was illegal to tell parents the results - a claim I find incredible - so has had to wait for a change in the law to make it possible.

But it will still be feasible for parents to opt out, even though the evidence is that most would prefer to be told. A poll in June by MPG, the media agency, found almost 90 per cent of its panel of parents in favour of being told. More than 70 per cent said that parents should not be allowed to opt out.

Nobody is suggesting that fat children should be made fun of, or that their measurements should be made known to their fellow pupils. Being stigmatised as “Fatty” is no fun. The measurements are taken discreetly; the only people who would know the results are the children's parents.

Why is this important? There is evidence that parents who are themselves overweight or obese are poor at recognising the same problems in their children. What is bonny in the eyes of an overweight mother may be worrying to others who see the child as he or she really is.

The health implications of growing up overweight are significant. While many children will slim down as they grow, others will turn into overweight or obese adults, with a greater risk of heart disease, diabetes and cancer. No parent wants this.

The Government has set targets for halting the growth of child obesity, and missed them. It has set a new one - to be the first nation to halt the growth of child obesity.

Tam Fry, the honorary chairman of the Child Growth Foundation and spokesman for the National Obesity Forum, says that it has lost that battle already. France, Switzerland and the US already have evidence of a plateau in obesity, while in the the UK it is still going up.

He says that the Government has been too careful not to offend people, while the survey actually shows that parents want to be told. They're not all as devoted as that Scottish miner, but all, surely, should be given the facts. They can always chuck the letter in the bin if they really don't care. But I suspect few would.

Nigel Hawkes is the Health Editor of The Times

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