Arc takes the school to the streets Agency: Arc/Leo Burnett, Territory: Global, Verdict: 4/5 In the mind of the graffiti artist, good spelling is a low priority. If the act is one of rebellion, how better to rebel than against the Queen's English? So when Arc, an arm of the Leo Burnett agency, launched a campaign in which it corrected spelling and grammar mistakes in these furtive daubings, it was careful to label it tongue-in-cheek. The agency used paint pens and stickers to tackle graffiti across a swath of London's edgier districts. Nothing was out of bounds, with even obscene jottings getting the grammarian treatment. The stickers name Arc's client The Tutor Crowd, an online tutoring service keen to show tutoring as unstuffy. Ten days after its launch, the campaign - published as a Tumblr blog and promoted on Facebook and Twitter - had doubled inquiries for a free English tuition trial. Could this presage a new age of graffiti-based marketing? Hard-pressed clients might applaud the savings on traditional hoardings. But in a sign that the agency may not be wholly committed to the rule-breaking ethos, it points out the stickers are removable and will be taken down next month. Get down with the kids, by all means, but make sure you leave yourself a safety rope.