Brandalism Any advertisement in public space that gives you no choice whether you see it or not is yours. It belongs to you. It's yours to take, rearrange and re-use. Asking for permission is like asking to keep a rock someone just threw at your head.
BanksyI am unable to comment on who may or may not be Banksy, but anyone described as 'good at drawing' doesn't sound like Banksy to me.
BanksyWriting graffiti is about the most honest way you can be an artist. It takes no money to do it, you don't need an education to understand it, and there's no admission fee.
Banksy