A surprising case of official competence

An evening on the South Bank - a flash of steel in a dimly lit underpass - and a whey-faced character in a hooded top lunges at a woman with two ten-inch blades. She jumps backwards, screaming, "He's got a knife!" He looks beyond her, as if weighing the odds. Then calmly stashing his weapons, he lopes into the promenading crowds. A tall black man passes within feet of the scene, seemingly oblivious, also headed for the riverside.

Eighty-odd miles away, at a recycling centre in Peterborough, an operative makes a sad discovery. Lorries come here from all over the country, and one brings a consignment of paper-waste bags with, lodged among them, the tiny corpse of a newborn baby. The police are called, and sift through the rubbish, noting addresses on envelopes, hoping for a lead.

By chance, I will be interviewed about this incident, as I will about the man with the knives. And in the process, I will be forced to temper my prejudices about cops - and robbers.

You see, some junk mail of mine was found next to that little body, and I was with the woman who escaped a stabbing. And where I would have expected official indifference, ignorance and apathy, I encountered sympathy, intelligence and activity.

The South Bank scenario was the more surprising of the two. As we fled back to the car, my friend wondered if we should call 999 - perhaps give descriptions of both the white and black man (in case they were in league)?

Where I expected indifference, ignorance and apathy, I encountered sympathy, intelligence and activity

What's the point? I asked. They'll never catch him, and we'll either end up on a bizarre charge or being offered victim support. Still, she insisted. So I jumped out on Waterloo Bridge and told two officers: one a community support chap, the other a WPC.

And what do you know? They didn't waste time completing a risk assessment form. They simply listened to a brief description, then rushed off to investigate, radios crackling for back-up. We drove to my friend's place and encountered even more unwonted efficiency. On the warpath now, she rang the local police station and made a formal report, while I wondered if it was worth it.

Eight hours later, I had my answer. The duty sergeant was on the phone, the knifeman had been caught and was in the cells, and the case-preparation officers would be round to question us at our convenience.

When they arrived, they couldn't have been more charming - nor scathing of the penalties available to the courts - though the other policeman I've seen this week ran them a close second. It was only a bit of procedural, but he had expended commendable effort on it, even calling at my home earlier to leave his number. And when I was unable to assist, he didn't eye me askance, but said, "Of course, it's the mother we're worried about. So far as we know, she hasn't sought medical help."

Remember that black guy in the underpass? It turns out he wasn’t working with the knifeman

If she does, she might bear in mind my story. Two typically horrid spectres of the modern world touched my life last week, and I expected a response as dispiriting as the experiences had been disconcerting. But like me, she might find that people actually behave as they should - or better.

Remember that black guy in the underpass? It turns out he wasn't working with the knifeman. Nor, immune to south London savagery, did he just walk on by. He was a security guard from one of the nearby arts institutions. He'd spotted the creep behaving suspiciously and, as he was trained, had followed unobtrusively. After our fright, he'd phoned the police and guided them to the suspect.

When the case comes to court, I hope that between us we can prove the accused guilty. But whatever happens, one thing has already been proved. Some boys in blue are still holding the line. And big black men can actually be white knights.