Lady Anelay, a former JP, believes that in some parts of the country, the carrying of knives has nearly doubled in just two years. She says she has heard of two schools where over a quarter of the children are carrying them.

Make no mistake, schools are at the very heart of this. An enormously disproportionate number of knife crimes are committed by teenagers. Two out of every five knife crimes are committed just by those in the 15 to 18 age group.

How serious has the government been about tackling this? Well, it has not been making schools into knife-free zones, that is for sure. How many children were prosecuted for carrying a knife on school premises in 2004? A mere 39. The figure would be funny if it were not for the fact that the presence of knives in schools is precisely what has led to several deaths in recent years. But there is worse. Although all but two of the 39 were found guilty, only a single one was given a custodial sentence.

So here we have a knife culture that is growing fast and, in 2004, one solitary knife-wielding child in school was put in custody. What sort of message does that send to the large numbers of teenagers carrying knives in school? It tells them to go ahead. You probably won't be caught and, if you are, and if you are prosecuted, you still will not get any meaningful punishment.

The fight against knife crime has been feeble and totally inadequate. The amnesty, in the words of Dr Marian Fitzgerald, a former Home Office criminologist, "can't achieve very much". It is hard to resist the idea that this amnesty is, above all a political gimmick intended to give the impression that the government is going to make things better.

It is said that the value of the amnesty is 'symbolic' and it might make some children more aware that it is against the law to carry a knife. But those likely to worry about it being against the law are the ones least likely actually to use their knives. And even if a knife is handed over, there is nothing to stop an adult going out and buying another one the next day. A child would be able to get hold of one quickly too, even if it is simply by taking one out of the kitchen drawer.

What is needed is something far more radical. Schools where knives have become a problem need to be able to use metal detectors to make the schools safe. Surely that is the minimum that any responsible government would expect and demand. But unfortunately the schools minister, Jim Knight, has already snubbed the idea of metal detectors at the London Academy.

The government needs to use stop and search actively to find knives. When they find them, they should then prosecute unless there are some exceptional circumstances. And the courts, in turn, should treat the offence as a serious crime, using custodial sentences far more often than they do now.

Unfortunately, the chances of the government doing this are virtually nil. This is the government which has failed to build sufficient prisons. That is why serious offenders have been put in open prisons from which they have easily escaped. Our prisons are so full now that they have become like hotels in Cheltenham during the racing festival. They are extremely difficult to get into. You have to commit a very serious crime, preferably more than once, to gain entry. Those who are 'only' found guilty of carrying a knife are not going to be put in custody because there just isn't room.

This demonstrates the true lack of seriousness of this government in fighting crime. The use of an amesty is merely gesture politics. It is all talk and spin. What we need is a determined, hard-headed battle against the knives. If the government's attitude is not transformed, then more of the youths we see on street corners will be carrying these weapons. More children will be frightened to go to school at all and an ever-increasing number of Christopher Alamenes and Kiyan Princes will die, leaving their grieving parents behind.

This is the unedited version of my article in today's Daily Express.