It's impossible to predict which paintings will last and which won't. In New Orleans I painted on a dilapidated shop in a street littered with abandoned cars and rotting mattresses, then two hours later the piece was gone. It turned out I'd picked the side of a crack house and the proprietor didn't like the attention.

Although you might have to creep about at night and lie to your mum it’s actually one of the more honest art forms available. There is no elitism or hype, it exhibits on the best walls a town has to offer and nobody is put off by the price of admission.

But there's no way round it-commercial success is a mark of failure for a graffiti artist. We're not supposed to be embraced in that way. When you look at how society rewards so many of the wrong people, it's hard not to view financial reimbursement as a badge of self-serving mediocrity.

Nobody ever listened to me until they didn't know who I was

Graffiti is one of the few tools you have if you have almost nothing. And even if you don't come up with a picture to cure world poverty you can make someone smile while they're having a piss.

A wall is a very big weapon. It's one of the nastiest things you can hit someone with.

Nobody knows what you feel inside unless you tell them.