Closeted in the home or watched over by 'helicopter' parents, children lack much of the freedom they had only 50 years ago. What changed? Steve Humphries, who has made a new TV series on the way young people play, charts the rise of stranger danger.

British children's play has been transformed in the last 100 years. Up to the 1960s there were few children who didn't spend much of their free time outdoors, playing in the fields, parks, streets, back alleys, old bombsites and local beauty spots.

This play was unsupervised by mum or dad and children were free to go on adventures far from home. Sadly this world of independent child's play has today largely vanished. One of the important reasons for this decline is the inexorable rise of stranger danger and child abduction in modern Britain.

It was in the mid 1960s that this new threat to children's freedom really took hold of the popular imagination. Child murderers Ian Brady and Myra Hindley helped change the nation's attitude towards children's outdoors play. Their sadistic crimes became one of the most sensational television news stories of the 60s.

The impact this had on children's play is vividly recalled by many growing at the time.

"I still remember the feelings of terror at seeing Myra Hindley's face on the news, there was a kind of loss of innocence, you didn't feel safe after that," says Lancashire boy Steve Wakefield, born in 1955. "Up until then parents didn't worry too much about where you went and what time you came home. But afterwards they wanted to keep you in the street and if you weren't home by the time it was getting dark they were really concerned and you got into trouble with them."

The fear that it was unwise to allow children to play outdoors without parental supervision was heightened by some other major social changes that were increasing dangers on the streets. A huge rise in car ownership and road traffic proved a big threat to children's safety and to the way working class communities used their street as a playground.

Houses for high-rises

From the late '50s onwards traffic accidents involving children playing ball games in their street increased steadily. Slum clearance and housing improvement schemes inadvertently added to the loss of a safe outdoor play space for children. They swept away many thousands of Victorian terraced streets where children had once played, to replace them with high-rise estates.

For generations neighbours and extended family members had kept an eye on children playing in the streets, stopping them from getting into serious trouble and checking on any strangers passing by. Modern high-rise estates broke up extended families and made this kind of informal policing of children's play virtually impossible. With no adult supervision the opportunities for child molesters and paedophiles increased.

There are few reliable statistics on stranger danger and the increase in child molestation and abduction. It can be said with certainty though that the number of reported cases remained extremely small. A much greater threat to children's lives was road traffic accidents - made worse by the increasing number of parents who began driving their children to and from school in order to protect them from the dangers of the outside world.

In parents' minds however child abduction often appears a greater and more insidious threat. The flasher at the school gates and sexually motivated attacks on children are nothing new, but in the television age these fears have been fuelled by intense media coverage of stories of child sexual abuse, abduction and murder.

The James Bulger case in 1993, the abduction and murder of Holly Wells and Jessica Chapman in Soham village in 2002, and the Madeleine McCann disappearance in 2007 are three of the most dramatic examples. All had a huge impact on attitudes of parents, making them more inclined to keep children indoors and to carefully monitor their children's outdoor activities.

Fat, angry, isolated

There is little doubt that parental fears of stranger danger have been an important factor that has helped drive a generation of children indoors. Recent surveys show that most children spend much more of their free time playing indoors than outdoors - a complete reversal of the play habits of children in the 1950s and before.

Growing affluence and the child-centred society has certainly not brought with it a richer outdoor play experience for children. The physical and psychological consequences of this lost world of children's play are now beginning to be felt, most obviously with the well documented increase in child obesity, child aggression and the isolation of children who now spend most of their free time indoors.

Quite apart from the health benefits of children spending free time playing running, chasing and hiding games in the streets and fields, independent play also taught them important social skills. There were inevitably disagreements and upsets over who were the winners and losers of all the games, but resolving them without parental interference helped the children grow up.

As Laura Hopkins, 60, from Manchester remembers: "If you were losing you'd go in and complain to Mum but she had no sympathy for you because she'd know it was just a bit of a disagreement, she'd say sort it out yourself. So 10 minutes later you'd be out on the streets again and you learned a lesson from that."