In these straitened times, it's good to know that jobs are still being created. A quango called the Independent Safeguarding Authority, which will open this October, already has a well-staffed helpline and is advertising for ICT (information and communication technologies) and finance specialists.

Never heard of it? You soon will. If you are one of the 11.3 million people who might, in the course of your work, come into contact with children or “vulnerable adults”, you will be paying for the privilege of being vetted by this new authority. Its net will catch almost everyone in the NHS, even cooks. It will encompass accountants and board members of charities. It will include anyone generous enough to offer work experience to a teenager, or a bed to a foreign-exchange student. It will vet a quarter of the adult population.

Just think: any one of those 11.3 million people could be a paedophile. And think again: this gargantuan system would not have prevented Ian Huntley from murdering two schoolgirls in Soham in 2002, even though that awful murder was what prompted the invention of the Independent Safeguarding Authority.

Huntley was a school caretaker. But that is not how he met his victims, Jessica Chapman and Holly Wells. They went to a different school. They met Huntley because his girlfriend was a teaching assistant. They stopped by her house to see her, she was out and Huntley invited them in. He could have been a dustman or a rocket scientist and had the same opportunity. But that cuts no ice with the bureaucrats.

None of us wants a Huntley in our schools. The Criminal Records Bureau (CRB) was heavily criticised for having licensed him to work as a caretaker when he was suspected of offences including rape and indecent assault. The problem was that his only conviction was for riding an uninsured motorbike. Now the CRB tells potential employers about allegations, as well as convictions.

This can ruin innocent people's careers. Last year, a man named John Pinnington was sacked as the deputy head of a college for autistic children in Oxfordshire after a CRB check revealed an unsubstantiated allegation of sexual abuse. It had been investigated and dismissed by the police, but Mr Pinnington's employers took fright.

Paedophiles represent one kind of danger. Elevating malicious gossip to the status of a criminal offence represents another. When pupils realise that they can get a teacher sacked by spreading rumours about him, we really will have institutionalised evil over good.

But even this is not enough to satisfy the zealots. Under the Independent Safeguarding Authority, it will become a crime for any relevant employer to hire anyone without an ISA licence. Employers who make their own judgments about whom to trust will face a £5,000 fine. The only people to decide who is employable will be the unelected ISA board, which appears to be made up mainly of professional quangocrats and the children's lobby.

If this sounds impossibly Orwellian, look at what has happened in Scotland since a similar scheme was created three years ago. In East Renfrewshire a father whose son suffered from Asperger's syndrome was told that he could not get on the school bus to do up the boy's seat belt without a disclosure check. After an outcry, the local council announced that children would be taught to do up their own safety belts, and that no parents would be allowed on school buses.

Paedophiles have made the bureaucrats all-powerful - except in the small matter of keeping children safe. The massacre of 16 children at Dunblane Primary School, which is often cited in Scotland, could not have been prevented by vetting. Thomas Hamilton, the gunman, was not employed by the school. He had been sacked by a Scout group that was alarmed by his taking pictures of boys. That Scout group protected its boys by using common sense - not by box-ticking.

Common sense protects children better than bureaucracy. It's like crossing a road. You can never predict accurately which cars will stop. You have to teach children to make their own judgments about when it's safe to cross. Similarly, you have to teach children to judge whom to trust and what constitutes strange behaviour. The vetting schemes that we are creating tell children to suspect everyone, and encourage adults to retreat. So children who are actually in trouble have fewer and fewer people to turn to.

I still remember the kind man who grabbed my toddler in a park when he was heading full tilt for the pond. I was heavily pregnant and could not run. But I could see his fear that I might accuse him of something. I also remember the hostility I got from a mother when I thought her five-year-old looked lost. These experiences are chilling. Ask yourself if you would stop if you saw a small child on its own. A lot of people are suddenly less sure.

Oblivious to the corrosive effects on society, the bureaucrats keep upping the numbers to be vetted. The Independent Safeguarding Authority grows bigger and bigger. Its launch has been repeatedly delayed as more complex software is devised to cope with concerns about data security. Josie Appleton, of the Manifesto Club civil liberties group, says that the cost of setting up the ISA will far exceed the estimated £84 million - five times what was first envisaged. The ISA will be a monster that assumes every volunteer granny is a monstrous paedophile. And everyone who is vetted will have to pay £64 for the privilege - £28 to the ISA on top of £36 to the Criminal Records Bureau.

The road to political oblivion is paved with good intentions out of control. More than 80 per cent of attacks on children are made by people they know. A third of sex crimes are carried out by adolescents, who will not be vetted. If the Government really has £84 million to spare it should be treating sex offenders, not subjecting millions of decent people to a modern inquisition.

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