The case of Kristian Holmes, the graffiti artist jailed this week for three and a half years after being convicted of 39 incidents of criminal damage and perverting the course of justice, brings back vivid memories for me. Like him, I led a double life – respectable job by day, graffiti artist by night. Like him, I'm a dad. And like him, I was caught and sent to prison.

I was sentenced to 16 months, of which I served four months in HMP Wormwood Scrubs and four months on home detention curfew, with the remainder to serve on licence. I find it interesting that Stuart Hall, the entertainer who was convicted of child abuse this week, got only 15 months. It seems to me that the courts value property more than they value the scarred life of a child.

There's a similar double-standard within graffiti art. Banksy will draw on the side of a building and the councils will protect him; they will fight over the piece of work going to a gallery because they want it to stay in their community. However, if another graffiti artist comes along, tags on that wall, the council will expect a criminal conviction. If Banksy got arrested and went to court I wonder whether he would suffer the same fate as Kristian Holmes? I doubt it. So when does graffiti become a crime?

I've met Kristian on numerous occasions and I know him as a tagger, or what we'd call a bomber. The court was told that for seven years he daubed his tag "on an industrial scale" across the south-east of England. Kristian, a father-of-two, worked as a respected property surveyor during the day, but in his free time went out with his spray can. If asked whether I like his style, the answer would probably be no, but at the end of the day he's getting his name – VAMP – out there, and that's all that matters.

The "VAMP" tag used by graffiti artist Kristian Holmes, who was jailed this week. Photograph: Central News

For a decade I was known as the most prolific train-writer in the country, using the tag NOIR. British transport police had a chart of the most-wanted graffiti artists, and I was No 1. I was proud of the title and relished the years of cat-and-mouse games as they tried to apprehend me. I'm writing a book called Addicted to Steel: the Story of London's Most Wanted Graffiti Vandal, which gives a detailed account of how our secret society exists.

Graffiti art originated in the late 1960s in Philadelphia in the US, and then arrived on the New York subway system in the 70s, so for me it's always been an art form based on trains. Painting on trains is very fast-moving – you paint it, it goes into service, it goes from one city to the next, one end of the country to the other, so everyone gets to see it for a certain amount of time, and then it gets cleaned off. To me it was all about the movement, the fluidity of it, rather than it being stagnant on a wall where most people wouldn't see it. I wanted my name all over the city.

By the time it came to England, the train scene was pretty much over in New York. Mayor Ed Koch and New York City Metropolitan Transportation Authority boss Bob Kiley promised to eradicate graffiti and made sure that anything that went into service was cleaned immediately. But a book called Subway Art, written by Martha Cooper and Henry Chalfant, opened our eyes to this new art form. As kids, we studied that book; it was full of trains covered in graffiti, with names like SEEN, SKEME, DEZ and FUZZ ONE. Two years later, another book, Spraycan Art, was published, which included graffiti on walls – colour productions by crews around the world showcasing their talent. By the mid-80s, the graffiti art movement had gone global.

Graffiti has been part of my life since I was 12. At school, I would sit in lessons drawing my name instead of listening to the teachers. When Saturday morning came, I'd grab my bag of paints, meet up with friends and go and paint.

After leaving school, I got a job in London as a property investor at a global bank, but I kept painting trains. I was often doing it four nights a week. On Monday mornings I would turn up having barely slept all weekend, and my colleagues would say, "Blimey mate, you look a right mess, what have you been up to?" I couldn't tell them the truth – so I told them I'd been out partying. And to me it was a party – but in a train yard instead.

My job was very target-driven: there were multimillion-pound deals and lots of foreign clients to socialise with. I'd have a few drinks, then go home, have an hour or so's kip, then assume this different persona, and be out until six or seven o'clock the next morning. People's perceptions of graffiti writers seems to run along the lines of council-housed and violent, when in reality many of us are upstanding members of the community in our late 30s and early 40s with good jobs and families to support.

In the early days I didn't have the internet to help me locate yards. I used to have a little train bible – basically a trainspotters' book that tells you where the trains are laid up and coupled in the sidings, and the best place to enter and take photographs of them. Only a few of us ever had this book – it was the holy grail to many train writers.

Gaining access to the train yards was difficult. You would have to take a pair of bolt cutters with you and cut your way through. I had a lot of yard knowledge – I did my homework. I would watch the cleaners, follow the train drivers home and note what cars they drove. They used to activate the sensors on the yard fences about midnight; so if you arrived early, you could cut the hole without them knowing. You'd sit there for hours watching the security guards. It was the best game of cat and mouse you could play. Sometimes I've been so close I could probably whisper in their ear. They'd look around but wouldn't know I was there. Then when they left I would paint the train, take a photograph, and leave. The adrenalin rush was amazing, and difficult to replicate.

Both Kristian Holmes, pictured, and Glynn Judd had well-paid jobs by day, and went out with their spray cans at night. Photograph: Kevin Dunnett/Central News

The courts and the media like to make out that we cause thousands of pounds worth of damage to trains, and that it takes many man hours to clean them. But in fact the trains have a protective film on them and the paint we use is acrylic – it's water-based. Most train yards have a washer system, which we call the "buff", that takes about 10 minutes to clean the whole train, and that's it – it goes back into service.

I kept my double life secret for 10 years. During that time I travelled the world and met some amazing people, many of whom didn't even speak the same language, but we were all focused on the same thing – which was to go into a train yard and paint our names as colourfully as we could. I've had experiences I will always treasure.

Then one day I decided there wasn't much left for me to do. I hadn't been caught, everybody knew my name, I was well respected, I'd painted with some of my heroes and I thought now I needed to do something else. It wasn't divine inspiration – I didn't get a tap on the shoulder saying: "Now is the time to give up and redeem yourself" – I just started falling out of love with it. I gave up working in the City and I went back to college to retrain. I started getting involved in community projects and workshops for kids; I was even asked to help paint the Dizzee Rascal house for the Olympics opening ceremony.

I started getting invited to art exhibitions of legal graffiti writers' work. After a year of not painting illegally, hoping I'd been forgotten about, I started attending these events and doing gallery shows. I put my name out there and was doing good things, I thought. But the British transport police graffiti squad attend those events, too, and take covert photographs of everyone. They took a photo of me, studied it and realised who I was. They had been chasing me for 12 years and now they had me on camera. They started building a case based on that one photograph. They didn't have a single picture of me committing an offence, but they went to Yahoo, Google and Flickr and got permission to download all my conversations with magazines and websites.

Is Kristian Holmes's disproportionate sentence going to be a deterrent to others? No. People who commit criminal damage will carry on regardless of the sentence they get. It's the justice system and how it deals with sentencing that needs to change. How can judges justify giving harsher sentences to graffiti artists than to paedophiles and rapists? If you really want to stop criminal damage, you start with educating kids in schools.

I was sitting on a beach with my six-year-old daughter recently. I picked up a stone and started writing in the sand. She said: "You shouldn't do that, Daddy." I said: "But I'm just writing our names." She took the stone off me and burst into tears. I couldn't understand why it was a problem. Whereas my little one seems to know already.

As told to Aida Edemariam