In America they do things differently, with security men paid to police the corridors and keep out troublesome elements (aka T Blair). The suggestion that similar measures should be taken over here has alarmed some commentators who seem to believe that schools should be open to everyone except the police officers who might be able to control them.
Violence and theft in school is somehow seen as the responsibility of teachers who ought to be able to control their pupils better. This is arrant nonsense. We don't train up doctors to be able to deal with street crime. If a disruptive individual starts smashing casualty, then security staff or the police deal with him, and no one complains that doctors aren't up to their job. Medics cure. Teacers teach. And if some thug is terrorising kids then he or she needs to be dealt with by professionals.
Speaking as a parent, I want my children educated by people who have been trained to inculcate knowledge, not experts in unarmed combat and crowd control.
Badly behaved pupils are not the responsibility of teachers. This may come as a shock to some, but children are the responsibility of their parents. If kids arrive at school incapable of behaving politely or respecting the property of others, then that is because their parents have let them down. It is not just unreasonable to expect a teacher to put right parental failure, it is outrageous.
Teachers have a great deal to achieve in the school day. They should not be expected to double as policemen and social workers. Leave teaching to professionals and if your school is being disrupted by thugs, leave them to the professionals too. Personally, I'd be happier having a plain-clothes police officer in my children's school than some vote-catching, headline-grabbing prime minister.