With motion-detecting cameras being brought as the latest weapon in the fight against graffiti on trains, BBC News Online's Finlo Rohrer speaks to a former teenage tagger.
Richard Sen is now a DJ and musician
Richard Sen is now a successful DJ, playing in clubs such as London's Fabric, but in the 1980s he was a "tagger", leaving his name logo all over London's public transport system.
"I started off doing my 'Coma' tag on the Metropolitan Line. I was from Wembley and that was my line.
"We would spend every day tagging the inside of the trains. The more people who see that tag the more you are getting 'up', you are getting your tag across the whole city.
"We would spend all day in a train yard. We were one of the first people to do a whole car top to bottom. We did a whole train once, about 20 of us.
"It was pretty reckless, walking down train lines in the middle of the night. Graffiti is a really organised thing, it is a full-time thing, you got up and that was your life."
He said increased security meant the graffiti that covered trains today was far more basic.
"It was easier then. Now they have got cameras, they have got fences and dogs, and probably guards in yards. They just didn't expect it then. Now because of all the security it would be a lot harder.
"They haven't got enough time to do anything good."
The 35-year-old - who now runs record label Mixed Blood - said in his teenage years he had needed a way to express himself.
"It was a phase you went through. It was just a way to get noticed, to rebel and get attention.
"The people who did it were special people, really obsessive, a bit mad, all eccentric.
"It wasn't blacks, whites or Asians in particular, it was all different backgrounds, middle class and working class kids."
Any stretch of graffiti can be the work of dozens of competing people
After brushes with the law during tagging missions, Sen eventually found himself imprisoned.
"The first time I went to a detention centre, to Hollesley Bay, for a two-month sentence. I had been arrested first for doing a wall and got a two-year conditional discharge.
"Then me and a friend were arrested in Stanmore [the end of the Jubilee Line] in the yard.
"They sent us both down. It didn't stop me, it made me worse. The detention centre made us more angry and more bitter about it."
In 1989 Sen had a second spell inside but he had already started to move away from graffiti.
"The next time I got done for everything under the name 'Coma', it was something like £50,000 of damage.
"It didn't matter. I had stopped by then anyway but I got six months. I was sent to Huntercombe detention centre and I was in Brixton prison for a week with IRA terrorists and drug dealers.
"I had grown out of it and started going out clubbing. Some people I know went on to make music, but one of my best friends grew up in a children's home and was obsessed with graffiti but is now doing a PhD in religious studies in Oxford."
In Sen's mind, teenage tagging and the more sophisticated graffiti that finds its way into art galleries cannot be separated.
"You've got to go through the whole doing things illegally part. I've done record artwork. Tagging is all part of it, that is how you start."
Sen has no regrets and is not repentant for any damage he did, viewing a train covered in tags as something worth seeing in its own right and ignoring those who are repelled.
"They are a bit narrow-minded, they are not looking at the whole picture. They think it always means there is other crime as well. But I don't care, I like to see a train that's covered. I've got older and I still think it should be there."