In 1904 the British government was so appalled by the state of the scrofulous and mangy recruits who had turned up to enlist for the Boer War that it instigated the first serious examination of the nation’s health.

The report of the Interdepartmental Committee on Physical Deterioration threw up evidence of such shocking social insufficiency that the new Board of Education was obliged to create a School Medical Service to monitor children’s health.The service’s early reports from 1907 onwards make grim reading: children fainting with hunger or bent double by rickets were commonplace. Thousands were killed or maimed by diseases such as smallpox and diphtheria.

The turn of this century gives us much to celebrate in terms of children’s health, in that many such diseases have been banished by the discovery of antibiotics. But spectres every bit as horrible have taken their place.

Some, such as malnutrition, never really went away. When free school meals were introduced in 1906, the chief medical officer of the Board of Education reported a “considerable number of children” with malnutrition. School meals and free milk (which arrived in 1921) undoubtedly helped, with children at their best-nourished immediately after the Second World War. Food may have been scarce then, but at least it provided a balanced diet.

Today the free milk has gone and children again suffer from malnutrition, not through deprivation but from being overly dependent upon fizzy drinks and chips. The health implications of this (heart disease and osteoporosis in later life) have so alarmed the Government that it is preparing to introduce minimum nutritional standards for school meals.

Children’s health today is being further compromised by widespread inertia. One hundred years ago, the average school child would have walked to school. Now children are invariably ferried there and back. As a result many are fatter and less fit than their forebears, with a dangerously sedentary pattern being established for their adulthood.

Twentieth-century ills have gradually become more psychological in nature as the physical threat of disease has diminished. More children suffer from depression or stress than ever before and suicide has become one of the top 10 causes of death among young people. Eating disorders such as anorexia and bulimia have escalated as young girls try to conform to a popular ideal of snake-hipped lissomeness.

Smoking behind the bike sheds would have been less common at the start of the century, for the simple reason that children could, in theory, smoke anywhere they liked.

Tobacco sales to minors became illegal in 1908, but it was not until 1962, when the perils of tobacco were made plain, that schools were told to “discourage” their pupils from smoking.

During the first half of the century cases of teenage drunkenness were isolated. In the 1950s, however, the increasing availability of alcohol led them to rise by 40 per cent.

Young people under 18 are now prohibited by law from buying alcohol, but this did not stop drinks companies from developing a brand of “alcopops” pitched directly at the youth market.

The swinging Sixties saw, perhaps unsurprisingly, the start of growing drug use among young people. Between the years of 1960 and 1967, the numbers addicted to drugs rose by over 300 per cent.

The arrival of Ecstasy in 1989 held particular dangers because its effects were so appealing: it was cheap and made users extrovert, sociable and able to dance for hours. It also went on to kill a number of them, as did the new menace of solvent abuse. Recent figures from the Office for National Statistics show that drink and drug use among young people is at last beginning to fall. Teenage pregnancy, however, continues to climb in the UK and is now the highest in Europe. This, like many other health issues, is most likely to affect those living in poorer communities, often where there is already a history of crime, drugs or poor parenting.

There is, however, one health hazard that is the same today as it was 100 years ago, and which transcends social and geographical boundaries: the head louse.

In 1902, one of the country’s first school medical officers, Dr James Kerr, was horrified to discover that children in a London school were “encrusted with scabs, exudation and lice”. Today two out of every three schoolchildren will, at some point in their school lives, go home with these unwanted guests.