You stumble in just before dawn and you're both too wired to sleep, so one of you puts the kettle on while the other rolls a joint and the gossip begins. Who got off with whom, what so-and-so was wearing, and didn't Sean look a state? You listen to something ambient and drink your tea while watching MTV with the sound down. You remember being given a plastic bag as you left the club. It's still in your jacket pocket. You open it and 25 pieces of glossy coloured card fall on to the floor, each one advertising a night-club or pay party coming up in the next fortnight. You pick through them, comparing names and graphics, and before you know it you're making plans for next weekend.

You've just been 'done' by the Flying Squad.

The Flying Squad is the principal conduit for a growth industry that emerged in the late Eighties. Until then night-club flyers - small handbills listing the time, date and address of events - were tawdry and monochrome, often done on a photocopier. But the acid house craze, coinciding with the final flourish of Thatcher's economic boom, changed all that forever. As increasing numbers of promoters tried ever more extravagant methods of luring punters to their oversized events, everything got bigger and bolder: from venues and PA systems, down to the humble flyer.

These days club flyers are a bona fide business, providing work for designers, printers, distribution companies such as the Flying Squad and, at the end of the line, dozens of casual workers who stand outside night-clubs in the small hours, handing them out. In any week there are up to 100,000 night-club flyers circulating in London, half of them printed in colour. Piles can be found in trendy record shops, boutiques and coffee bars. But the majority will pass through the Flying Squad's east London offices, where they are sorted into 'smart packs' for distribution by hand.

Russell Cleaver, 36, got to know the night-club circuit as a soul boy during the late Seventies. A former road haulage traffic controller, he reluctantly started handing out flyers after being made redundant in 1990. 'I started on the house scene,' he says, 'then did a lot of the big, outdoor, hardcore rave stuff. Over the years I got more and more of that work, and built up a reputation and trust.'

After a couple of years working 'unofficially' he formed the Flying Squad in May 1992. 'Now I do everything,' he says, 'jazz-funk, hip-hop, jungle, hardcore, house, techno, trance, swingbeat, soul, funk. The whole spectrum.' But his is no scatter-gun policy: each flyer is delivered in a relevant 'smart pack' package, and given away at an appropriate venue. 'There's no point in us giving flyers for a techno club to a funk crowd, and vice versa.'

'We started in 1990 at the height of the recession,' says Daniel Terry, his 21-year-old right-hand man. 'But this whole scene wasn't affected by it, because it's mainly young people, without mortgages. They just want to go out every weekend and get out of their head, and they've got the money to spend. So our business grew, and is still growing.' In four years, Mr Cleaver estimates, his company has distributed something like 10 million flyers.

In the here-today-gone-tomorrow world of nightlife, flyers are crucial. They put the relevant information about an event straight into the potential customer's sweaty palm. A good flyer will be taken home to be pinned up, or shown to friends, and can make the difference between moderate attendance and queues around the block.

Philip Sallon, a successful club promoter for almost 15 years, had 8,500 intricate, fold-out Victorian-style cards printed for his Ms Mud May Ball in London last weekend. He regards the pounds 1,500 cost as money well spent. 'If they're imaginative, they attract the right kind of person.'

Mr Sallon refuses to call them flyers, preferring to use the word 'invitations'. He also refuses to use a distribution service, sending most out on his mailing list, and dispensing the last few hundred personally as he flits from club to club. He likes to see people's reactions when he hands them one of his elegant cards. 'It all comes down to ideas,' he says. 'Anyone can spend a lot on a useless, tacky invite.'

Rick and Debbie, the first-names-only husband and wife team behind the legendary Pushca parties, have a reputation for producing some of the wittiest flyers in clubland. Banknotes, matches and various cut-out shapes - some decorated with coloured 'jewels' and ribbons - are just some of the ideas used to give an idea of the high production qualities associated with Pushca events. Most recently, they had thousands of yellow Marigold household gloves fringed with purple 'ostrich feathers' to advertise their Housewives' Choice party. 'It reminds people that what we do is a bit special,' says Rick.

The very best flyers become collector's items. The walls of the Flying Squad's offices form an impromptu gallery, featuring a wide selection, with noticeable stylistic differences from genre to genre. 'The house and garage clubs tend to have jokey names and pictures of TV celebrities like Harry Enfield or Vic Reeves,' says Daniel Terry. Others feature less politically correct stars such as Sid James, and names like Leave My Wife Alone.

A minority are blatantly sexist in their depiction of topless women, but the classier (some would say more pretentious) house events opt for glamorous women, particularly Sixties icons such as Jean Shrimpton or contemporary supermodels. As a rule of thumb in the graphic language of nightlife, this signifies a 'glam' or 'loved-up' night, with drag queens and illicit substances.

Techno flyers, on the other hand, tend to be futuristic and earnest; though there are examples of wit: Wandsworth's Final Frontier club recently issued a four-page 'airline ticket', giving full 'flight details' of the month's attractions.

The hardcore rave style is best described as post-psychedelic, featuring psychotic-looking cartoon ravers, rendered in airbrush. Pez, a self-taught 24-year-old artist from Southend, is widely acknowledged as the forerunner of this style. He made his name during rave's boom years, and was instrumental in persuading promoters to spend on bigger and more colourful posters. 'I used to carry my portfolio around all night, then go and hassle them at four o'clock in the morning until they gave me the work,' he says.

It was by distributing A3 poster-flyers such as Pez's that the Flying Squad was established, but things have changed. 'That was when the big outdoor raves were booming,' says Daniel Terry, 'events with 25,000 people like Castle Donington in summer of 1992. Since then the laws have changed and people have gone back to the clubs. For the last two years the club scene has been phenomenal. That's where the money's being made.'

What of posterity? Is anyone keeping this most ephemeral of ephemera? Well, Pez is trying to have a book published, and the Flying Squad's Cleaver and Terry have considerable collections. The V&A has not been in touch, but the Squad does a lucrative sideline in selling packs of unused flyers by mail order, at pounds 1 each.

'We were making pounds 500 a week on that alone at one point,' says Daniel Terry. Most of the buyers, he says, are 15-year-old boys, too young to attend the raves but fanatical about the fashions and music. 'They use them to wallpaper their bedrooms.'

In the end, a night-club is only as good as its promoter, no matter how slick the flyer. 'Nightlife is a tough business,' says Mr Cleaver, 'and you've got to put the work in. I could lie to them, say: 'Put more flyers out, do 100 clubs. You'll be banged out.' But it doesn't work like that. You need all the right ingredients plus flyers, advertising, the whole works.'

And most important? 'Good word of mouth,' says Mr Cleaver with a smile. 'You can't beat it.'

(Photograph omitted)