All human life is here, innit: What used to be a no-go area is once again the beating heart of London. Jim White joins the hordes who have rediscovered Leicester Square

By 10 o'clock, Sanna, a student from Casablanca, had failed to sell any of the flashing red plastic roses she had in her bucket.

'I have only once sold them all,' she said. 'I stayed here till four in the morning to do it. Most times I sell maybe three. About once a month the black boys come along and steal the whole bucket. They call it taxing.'

Odd, then, for a financial return that rarely tops a fiver, that Sanna has spent every Friday night for the past year standing in the same place outside the Swiss Centre in Leicester Square: just her, a bucket and a lot of unsold plastic.

'I come here because I enjoy it,' she said. 'I love watching the people go by. I daydream about who they are and what they are doing. What they are doing mostly is not buying my roses.'

Now that spring is threatening, though, there is no better place for Sanna to be: the Friday night promenade through Leicester Square is in full bloom. Come out of the Tube station at about seven o'clock and you are plunged straight into it. The freshly erected heritage railings are completely obscured by the mill of people. Office workers hang around for their tardy dates; Danes in kagouls ask the newspaper sellers where Leicester Square is; groups of lads walk past in snappy shirts; middle-aged German couples in long green coats amble by, arm in arm; an American evangelist in a suit pursues two girls through the throng asking them if they have heard the good news. There are old and young, foreigners and day-trippers up from the suburbs, locals even, out walking the city streets.

Fewer than five years ago, however, Leicester Square would have been the last place most of these strollers would have risked their expensive heels; then the people hanging around outside the Tube were waiting for their dealer. Shabby through neglect, its central gardens left battered and unrepaired after the 1987 hurricane, it was London's Times Square, the place that made you wince every time you walked through it and saw the tourists thinking this was England.

In 1991, realising that they couldn't follow their usual approach to a problem property and flog it off for a penny, Westminster Council set about sprucing the place up. pounds 3.2m was spent on fancy pavements, cheering up the gardens, bringing in security patrols, putting Monet prints on the walls of the underground lavatories.

But what really made the place live again was not of Westminster's doing. It was that the people came back and reclaimed the streets. And they didn't come for the conveniences, even if there is a 'parent and baby room' in the new Gents.

What the people came back to do mostly, it seems, is to wander from queue to queue. Twickenham on Saturday would have been pressed to better the Friday night lines in Leicester Square. The new American retail outlets which supply graze food to the promenaders - Hagen-Daz, Baskin-Robbins, Burger King, even the bizarrely named I Can't Believe It's Yogurt] - have people patiently filed up outside most of the night.

Buzzing parasitically around them is the unlicensed commercial activity of the Square. Entertaining those waiting outside Adam's Rib - 'the place for ribs' - you can find a rapping tap-dancer, his hat empty. Next to a man selling African tribal artefacts, half-a-dozen pavement artists work the line for the Empire cinema, ready to pack up their easels at the first sign of a policeman.

'You find no English artist here,' said Alex, an art student from Moscow. 'We are from China, Serbia, Poland. The English would not work for this money.'

Alex scribbles portraits in pastel from six o'clock to midnight every Friday and Saturday. He makes, if he is lucky, pounds 15 a night.

'I send that home to Russia. It is good money there,' he said, explaining that he manages on a small grant himself. 'The thing that pisses me, though,' he added, 'is those guys over there,' nodding in the direction of a Ghanaian flamenco troupe. 'They play the same bloody tune hour after hour and they make a fortune.'

Some of these queue workers are not offering anything, except salvation. Michael, a Scouse evangelist, has been in Leicester Square every weekend for eight years. With his spotlit easel, oils, canvas and sophisticated proselytising-while-painting technique - a sort of happy, clappy Rolf Harris - he reckons Friday night is all right for preaching, a chance to get a little converting in.

'This is a great place for us to be,' said Michael, waving his paintbrush at the thousands of people. 'On a Friday people are relaxed, no one is in a hurry. They stop and listen. Of course we don't do the converting. He does.'

The biggest queues are for the cinemas. The Empire and the Odeon have spent as almost as much as Westminster sprucing themselves up, hoping to attract some of the new money coming into the square. But the best of the lot is the new Warner West End, which now boasts simultaneous showings of eight films.

Here dozens of new ways have been introduced to make it easier for customers to open their wallets. Booking is electronic, conducted by sharp boys in blue blazers and Star Trek telecom head-sets. They work under narrow electronic noticeboards announcing availability for screenings of FREE WILLY, COOL RUNNINGS and IN THE NAME OF THE FA . . . (a thriller about the home life of Bert Millichip, presumably).

Inside, to prevent you wasting a moment without spending money, are ranks of video machines and a fuelling station offering buckets of drink and servings of popcorn big enough to keep a bulimic happy through the uncut version of Lawrence of Arabia. In the theatres, the seats have plastic claws in their arms to hold the vast quantities of produce apparently required to see you through a film.

The place is always full, attracting a polyglot of cinema-goers, drawn as much by the art of The Piano as the blood-spilling of Carlito's Way. After the films, the different audiences collide in the lavatories. Last Friday, for instance, at 11 o'clock, a teenager with hieroglyphics carved into his hair stood next to an Asian man.

'What you seen?' said the boy.

'In the Name of the Father.'

'That Guildford thing?' said the boy. 'Miscarriage of British justice or what?'

'Happening every day,' said the man.

'Innit,' said the boy.

As the evening progresses, the queues out on the Square change character. In line in front of the Empire Ballroom, teenagers shuffle nervously, hoping to pass inspection by the bouncers.

'Basically no trainers, no boots,' said a thick-necked doorman, explaining his footwear policy. 'Yeah, suede's all right, but you probably won't pull anything wearing it.'

Next to the Ballroom the queue for the late-night screening at the Empire cinema is made up almost entirely of Chinese people. Does the Empire screen Chinese films late at night, then?

'Nah, mate,' said a smartly dressed man in the line. 'We're waiting for Schindler's List.'

Only after closing time, as the incidence of public snogging and stomach spillage increases, and Michael the Evangelist has packed up his easel ('a drunken woman threw my paints all over me the other week'), do the crowds begin to thin out. But even then the beat policemen insist they do nothing more strenuous than direct drunks to the night buses and chivvy along the homeless who have spent the night swapping cider philosophy in the entrance to Cranbourn Mansions.

'Bag-snatching, that's about as bad as it gets,' said one policeman. 'Basically this is a bloody nice place to spend the evening.'

Sanna, still at her post as the discos emptied, her roses still flashing, would agree.

'It has been a good night,' she said. 'The black boys didn't take my bucket.'

(Photographs omitted)