Thousands of police hours and hundreds of thousands of pounds of public money has been spent investigating a crime that has caused widespread alarm but for which no one has been arrested.
Paedophiles and childless women have traditionally been seen as the culprits in reports of people masquerading as social workers and attempting to snatch children. But criminologists now think most incidents are no more than misunderstandings or cries for attention, leaving possibly only a handful of genuine cases.
But not one case has been confirmed. Using press reports from the past five years, police forces contacted in the areas of the reported crimes all said they had not arrested anyone.
In 1990, the biggest initiative took place in South Yorkshire, where Operation Childcare gathered 250 reports, and involved 23 police forces. A year later no one had been arrested and of the 250 reports police believed only two were genuine and 18 worth taking seriously.
Det Supt David Foss, in charge of the operation, said the main difficulties they faced came as a result of people believing media hype. He was convinced some of the complaints were genuine but thought it was blown up out of all proportion.
The lack of arrests and the fact that so many episodes are unsolved or proved to be false makes it impossible to tell whether most are hoaxes or genuine misunderstandings.
While Operation Childcare was in existence, a South Yorkshire police spokesman admitted that alleged bogus officials investigated ranged from genuine social workers, door-to-door salesmen, canvassers and researchers to portrait photographers and a television crew.
Lothian and Borders Police set up a special unit as a result of spates of reported incidents since 1990. Chief Inspector Douglas Watson said: "There have been no arrests. We disbanded the squad in July last year. The bottom line is there is more than one team [of people] involved. There were ones we felt were worth investigating but a lot of the reports were malicious by attention-seeking people."
Criminologists searching for motives in genuine cases support the theories of self-appointed child protectors - people convinced children are being abused - or those trying to gain attention with false claims.
Dr Bill Thompson, a forensic criminologist at Reading University, lists four categories: "Some are paedophiles, some are upset women. The third person is a self-appointed child abuse investigator . . . The fourth group are copycats - someone with nothing better to do."
He said when reports got in newspapers, the copycats started. "Or it could be the second group again - a woman who has had a miscarriage or lost a baby. It could be someone who wants to borrow the baby or, worse, a person wants to believe it's theirs. Or finally, others want people to believe them in order to get attention, favours or sympathy."
Ray Wyre, a sexual crimes consultant who worked on Operation Childcare, saw them as self-appointed child abuse investigators. He finds it difficult to blame paedophiles or would-be mothers: "To do it in this way is an incredibly high-risk strategy," he said. "Also, no babies were actually taken, although some children were examined. What on earth was going on? There are many other ways getting hold of a baby.". But he refused to accept that the cases were all mistakes or hoaxes.
Meanwhile, social and health workers have tightened procedures. Paul Fantom, policy officer for the British Association of Social Workers, said steps had been taken locally to tackle security problems, but he called for a national register of social workers.
A Health Visitors' Association spokeswoman said: "We stress people must check identification and health visitors come with an appointment."
'She said she was the new health visitor'
Anne Wylie, who experienced a person posing as a health visitor with the apparent aim of examining - or even snatching - her 20-month- old son, is deeply critical of those who dismiss all cases as misunderstandings or cries for attention, writes Glenda Cooper.
Since last October, when a woman called at her house in Hamilton, Strathclyde, wanting to see Robert, Mrs Wylie says she feels like "hiding her son in the washing machine" when strangers call at the door.
"I thought it was strange to start off with, as no one usually comes to my back door," she says. "This woman said she was my new health visitor and she had come to check his medical records. My son had been in hospital, he was an asthmatic.
"I said to her 'Do you have identification?' and she said 'Och, I must have left it in the car,' something my usual health visitor never does. I looked at the car and there was a gentleman in there smoking a fag - which again was strange as you wouldn't have thought health visitors would.
"So I asked her my son's name and she hesitated. But then she got out this file and I don't know if it was my son's but she seemed to know all his medical history - how long he'd been in hospital for and so on.
"She was talking to my son but it was pouring with rain and I said we'd all better go into the living room. I took my son inside and she was away."
Mrs Wylie rang the office of the woman who had been her health visitor and found that she had not been replaced. She reported the incident to the police, but they have not been able to track down the woman or discover a motive.
The shock of the narrow escape hit Mrs Wylie and has affected her since. "I'm very wary now," she says. "I don't like opening the door or talking to people I don't know.
"You should always ask for identification," she adds. "If I hadn't then the police could have been coming round to my home saying we haven't found Robert or we have found him but . . . It doesn't bear thinking of. You can't take any chances."
Mrs Wylie told the police that the woman was in her late twenties, about 5ft 4, slim with light brown hair and a small mark by her right eye. She was wearing a light blue coat, similar to that worn by nurses. The police said they were "treating the incident very seriously", but they have not been able to identify the woman concerned, and Mrs Wylie is worried she might try again with someone else.
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