On Saturday, May 25, 1968, four-year-old Martin Brown rose at 6.30am. He was a stout, healthy boy with wavy fair hair and a good appetite, and his first act of the day was to potter into the kitchen to fetch himself some bread and milk. He then climbed back up the stairs of his family’s Newcastle home to feed his one-year-old sister Linda, leaning over the side of her cot so she could grasp her cup.

Once he had got Linda up and dressed her, the pair waited till 9am to wake their parents, who always had a lie-in on Saturdays. Then Martin had a bowl of Kellogg’s Sugar Pops – his favourite – and went to put on his blue anorak. “I’m away, Mam,” he called out to his mother. And that was the last time she saw him alive. At 3.35pm that day, he was found dead in a condemned house. At first it was assumed his death was an accident. It only later emerged that he was the first of two victims of the child killer Mary Bell, herself just 11 years old.

“We didn’t think to watch when they came and went,” Martin’s aunt Rita explained later. “All the kids are all over the place.” During the day Martin was seen by workmen, by Rita’s mother and by Rita herself. At about 3 o’clock he called back at his own house to ask his father for money for a lollipop.

Putting aside for a moment its horrific and tragic ending, it was just an ordinary day in the life of an ordinary child from an ordinary, loving home. Nobody thought it odd that a four-year-old boy should be out of the house for six hours without his parents knowing where he was.

And yet reading the account now in Gitta Sereny’s 1972 book on the case, it seems extraordinary. The four intervening decades were but a blink in the eye of history. And yet childhood, and our attitudes to children, have changed almost beyond recognition. Looking back through the prism of the Bulger case and its aftermath, the events surrounding the crimes of Mary Bell cast a startlingly clear light on a time that, oddly, seems much more innocent than today.

The trial of Mary Bell, unlike that of 10-year-old Robert Thompson and Jon Venables in 1993 for the murder of two-year-old James Bulger, made few ripples in the press. The reports were short and factual. Mary Bell was described as a one-off, a psychopath, a “bad seed”. The social fabric remained unrent by the outpourings of grief and guilt which would accompany the Bulger verdict a quarter of a century later.

Children in the 1960s were what they were: good, bad, indifferent, even murderous. They were not, in the public imagination, the creation of their parents or of society. Whatever they did, we weren’t responsible. We are now. Gradually, a sense of guilt has built up. Dr Stuart Newton, the former head teacher who yesterday urged us all to take responsibility for Britain’s “feral youth” and who detected “the downward spiral of Britain,” is just the latest in a line of commentators who want us to believe we face a collective crisis.

Perhaps it is that sense of responsibility that weighs ever heavier on our shoulders now. Whatever the day-to-day realities of our children’s lives, they seem every year to be ringed more clearly by a halo of collective dread. We worry about their safety, their allergies, their weight, their educational performance, their behaviour. We even worry about their levels of anxiety, as they queue for counselling sessions.

A report by Unicef, the UN children’s agency, assessed the wellbeing of children in 21 wealthy countries, surveying such things as relative poverty, family relationships, safety and personal happiness. Britain’s children came bottom. Although only a minority felt lonely, lived in one-parent families or rarely ate a meal with their parents, they were still more likely to do so in Britain.

So, are our fears justified? Are we raising a generation of tense, unhappy children who will become tense, unhappy adults? Will the next generation drag itself miserably through its best years, worrying about its career prospects, its weight and its dysfunctional relationships? Is it growing up too fast, exposed too early to sex, drugs, alcohol and the consumer society? Or too slowly, never allowed out alone, looking forward to a life of student debt and dependency? Of course our children have material benefits of which previous generations could barely have dreamt and are hedged around with an ever-denser thicket of legislation designed to keep them safe. And yet, in making them daily more secure, are we losing some of the joy which seems central to our notion of what childhood should be?

Hugh Cunningham of the University of Kent and author of several books on the history of childhood, fears we may be. He points to a recent study by the Government’s Children’s Rights Director, in which children were asked their views on the most important things for them. “Staying safe” was rated above all else. When they were asked to name the greatest dangers they faced, “strangers” came top, followed by smoking, knives and drugs.

“I think no previous generation of children would have dreamt of putting that as the most important thing. What would you grow up like if you spent your childhood thinking you had to do a risk assessment every time you go out of the front door?” Cunningham asks.

Times recommends

• Live chat: Thrifty ways to update your winter wardrobe
• Is anybody out there really listening?
• Nutrition Q&A: Will eating late make me fat?