A lot of the big-name graffiti artists today who work for Adidas, Levi's or Fosters Ice - companies hell-bent on tapping into street culture and all the street credibility that goes with it - started their days in crews, teenage gangs which spent their evenings dodging transport police and speeding trains to "bomb" particular sites with their spray cans.
But London Transport prides itself on its clean-train policy, which sees trains scrubbed of all graffiti before hitting the tracks, and security around depots is also tighter than ever, making the murals of old just a memory. John Scobell, Graffiti co-ordinator for London Underground and British Transport Police, says he's no fan of graffiti, which is estimated to cost up to pounds 10m a year, but sounds almost nostalgic when he admits the standard of the art work is not what it was.
Scrawl, dirty graphics & strange characters, at Arc Arts and the Dry Bar in the Northern Quarter of Manchester, has dragged indoors some 20 graffiti artists who are making a living from their work - with a wide range of styles from the 3D lettering of Prototype 21 and the purist more old-school style of Kelzo, to the strongly figurative works of Mode 2 and the abstract, almost fine art designs of She One.
Graffiti first came to the UK from America in the Eighties as part of hip hop culture, together with rap music, break dancing and deejaying, which is why graffiti and music are inseparable. The artist Toshio Nakanishi says he even approaches his art and music in the same way: "In music, I take a sample which acts as a trigger. It's the same with art - find an image and build from there. Fragmented music, fragmented art." But while the art side of things has always lagged behind the success of the music, today the work of both American and British artists is gaining momentum all the time. "Some people are taking graffiti to another level, which borders on fine art," says Ed Matthews from Arc Arts.
She One is one such artist, whose elastic lettering has been stretched beyond recognition, creating stunning abstract works filled with energy and movement, which captures the speed with which graffiti, by necessity, has always been thrown on to the "canvas", be that the side of a train or a building site hoarding.
Tags in graffiti are all-important - dating back to the Sixties in America when city teenagers competed with each other to get their names on walls and trains as often as possible, and thereby earn instant street cred. From there bubble letters emerged; then 3D calligraphy; the tangled wild style, which only the initiated can hope to decipher, and finally the large figurative and abstract pieces which saw graffiti explode in New York in the Eighties when subway trains were covered in intricate of designs. But while Futura 2000, Mode 2 and Swifty are big names in the street art world of today they are not names known to the general public, although their designs appear on billboards, television ads and record sleeves for such companies as Grand Central records, Ninja Tune and Mo'wax.
A few artists still keep up their street work, although a lot limit themselves to tags. "Tags represent a search for fame," explains Ric Blackshaw, contributor to the book Scrawl... "No one outside that world knows you are that person but it gives you massive credibility if you're good." Kelzo is one tag that crops up all over Manchester: a personal brand name that doesn't have to be stamped on a piece of art to carry kudos.
Stick a company name next to that tag, and you inevitably have instant cool by association. "It's a way of tapping into something, and images can say so much more than the confines of grammar," says Matthews. "If a company uses an artist that designs record sleeves, they're making a link with that client straight away. People may not recognise the artists but they recognise the style and make the link between that band and that drink and that billboard and that record sleeve," he adds.
As well as hip hop, the artists are all obsessed and inspired by similar things, looking to comic book art (particularly the dystopia of 2000AD), sci-fi (the Star Wars films) and urban life. "It's about obsessions and it's generational," agrees Swifty, who's considered at the forefront of UK graphics. "It's the Thunderbirds and the Sixties for me and Star Wars and the Seventies for Mitch [who he works with]."
Phil Frost, whose pieces are filled with scratchy, toothy, alien figures, sees the urban landscape as a gallery: "Through skateboarding I began to look at the street as a gallery, seeing different obstacles, the textures on the roads and how walls were weathered.
"They create pretty abstractions like a gallery on the street." Like Nakanishi and other graffiti artists, he also sees his art and music as intertwined: "The thing that inspires me to paint is sound and music. When I'm really into painting I feel an impulse or rhythm and try to mouth the syllables. It's like I'm moving to the rhythm, freestyle, but instead of being abstract it's like I'm recording the nonsensical language of the people I paint."
Stefan Plaetz's exhibition piece is filled with furiously active, diminutive figures with startlingly coloured angular bobs: "My style is about what the world looks like from a moving skateboard. I give you a different perspective on cities than if you're in a car or on foot. Bodies in motion and flowing movements." There clearly came a point when yesterday's teenage graffiti artists had to earn a living and the commercial world beckoned. But to have conquered mainstream media while retaining its cool, highly marketable street image has been a real achievement.
Cosmo Sarson, who is known for his B-Boy Collection: five paintings of himself break-dancing down at the Tuffnell Park Hall of Fame (a wall constantly recovered with full-on, large scale murals) has no problem with the way things have turned out: "Artists aren't bohemians any more. They're selling trendy commodities . So if people want to buy branded art with a trendy theme, all I'm doing is creating something to meet the market."
Scrawl, dirty graphics & strange characters, Arc Arts and the Dry Bar, Oldham Street, Northern Quarter, Manchester (0161-236 9840) until 28 Nov. Scrawl..., by Ric Blackshaw, Liz Farrelly and Mike Dorrian, is published by Booth-Clibborn Editions, pounds 25