Joan Bakewell: And now here is the good news...

People rushed to help me - a teenage boy, a middle-aged man and an older Asian lady

Conflict and attack is believed to be the essence of a good column: rubbish this, trash that. Done with élan it can be hugely entertaining. Lynn Barber wins awards with newspaper profiles showing how awful people are, or occasionally how surprised she to was to find so-and-so wasn't such a shit after all. On the other hand, when newscaster Martyn Lewis suggested a good news agenda every newsroom in the country winced at his naïvety. People enjoy vigorous encounters. Next week I chair a debate that pits Richard Dawkins against Roger Scruton. It's already a sell-out.

So what you would enjoy now is for me to declare that Jeffrey Archer's novel about Judas is a shoo-in for the Booker prize, or that Gordon Brown is cuddly - which is what I happen to think. I'm not going to do either. I've a tale to tell of good things happening. You might want to stop here and look for something more likely to fuel the adrenalin.

This is what happened to me. I love station concourses: I really enjoy their air of bustle, the sense of everyone on their way somewhere; the tearful partings, the passionate reunions; all this and good coffee, cash machines, and shopping for socks and fancy creams. I walk through them with pleasure and enjoyment.

Except this time I didn't. This time I went flying, full tilt, across the glittering smooth paving of Waterloo station. The wheels of my suitcase slid away, my handbag shot somewhere else. My chin, wrist, hips and knees all spreadeagled across the floor. And this is London: bad things can happen. Bag snatched, case missing, at the least my plight totally ignored.

Wrong. Instead what happened was like a charity initiative test for Christian fellowship. People rushed to help: three in particular took time to attend to my rescue: a teenage boy, jeans and trainers, tousled blond hair, helped me up; a middle-aged man retrieved my case; an older Asian lady took me gently by the shoulders: "You've had a shock; I really think you should sit down." She showed genuine and continuing concern.

How unlike the image we're encouraged to have of the alienated city, people heartless and hurried, knaves ready to snatch your purse, young people indifferent and glued to their mobiles and iPods, and Asians who might, being Muslim, have a grudge to settle against society at large.

Such generalisations have become the glib shorthand of our culture. They don't even amount to seriously considered views, being nothing more than slack pub talk, often as a vent for personal frustration and anger. Of course, terrible violence happens. In London, small gangs of young men seem seized by the communal madness of a code that prompts them to shoot and stab each other. But millions aren't.

There's more good news. Only a few days ago, Linda and Richard Weeks advertised on 50 London buses for an egg donor to help them have a child. Within two days they had 60 responses: young women coming forward, willing to undergo uncomfortable procedures that will bring happiness to an infertile couple. With a cynic's suspicion, carefully nurtured by the climate of the times, my first response was to be wonder, "what's in it for them?"

Then I recalled my Waterloo experience and decided to go easy on cynicism and allow for the reality of kind people doing kind things. The world is full of them. They don't make the news. Why should they: no conflict, no abrasive comment. But the news agenda is so loaded towards what is worrying and distressing that it is colouring our outlook on the world.

Sure, there's child poverty, knives and guns, Iraq, torture, Darfur. But the feeling many people have, especially the old and those living alone, that they can't step outside without being mugged, is out of all proportion. Britain is not a sink of cruelty and vice. It is on the whole a benign and law-abiding country. That's how we are seen from abroad. It's why so many people want to come here.

The other image running parallel to the gloom and doom picture is one of London as the greatest city on earth, the world's financial heartland, a glittering capital awash with pleasure, glutted with haunts of delight and temptation, inhabited by stylish young people who, without effort, all have smart flats and glossy jobs. It's an image fostered by the commercials and full-scale feature films being made here. Foreigners certainly see us differently.

Last year more than 120 films were shot in London, mostly or partly on location. Woody Allen declared his love of our cloudy skies, made a sequence of three films, before switching his loyalties to Spain. David Cronenberg and Paul Schrader have been and gone. Now we learn Martin Scorcese is to film The Young Victoria on location in London. There's even a camera crew around the corner from where I'm writing this.

This is all evidence of London as the hub of a thriving film industry. There's even an agency devoted to smoothing the way for cameras and lights. What are they seeing that we can't? To observe ourselves as others see us might help redress the relentlessly downbeat mood of today's political discourse. There is more to Britain's way of life than crime statistics and Budget calculations. Oh, and there are now 30,000 brilliantly coloured parakeets in the trees of South-east England. Perhaps it's just spring.

Joan.bakewell@virgin.net