seldom catch anyone perpetrating a major crime. That's not the point. The prime police duty is to keep the peace. The offences that worry people and make them think their neighbourhood is turning sour are the rash of petty crimes: the snatching of bags or mobile phones, the drunken rowdyism, the graffiti smeared on walls, the aggressive begging. This is where the roving police officer can have a civilising influence. By comparison with cop fiction, it's a dull job: walking through dreary estates, peering into nighttime shop windows, looking down alleyways, noticing anything that seems amiss. But this is the job we're paying the police - very handsomely - to do. And surely, except in the most special, threatening circumstances, a police officer should be tough enough to do it solo. If not, he or she is in the wrong business.