Banksy gave up spraying freehand graffiti back in the early 1990s when he discovered that stencils were more “quick, clean, crisp, and efficient,” as he once told an interviewer. He didn’t care that other artists in his Bristol crew considered it cheating. “As soon as I cut my first stencil I could feel the power there. The ruthlessness and efficiency of it is perfect.”Banksy’s language here is telling. It is precisely the kind of strict, economical approach the anonymous artist has applied to his entire career, which has taken him, if not from rough working-class roots — his street cred is widely debated — then at least from suburban Bristol