Drawing on the back of a bus

I've done some ads for Stoke Newington School & Sixth Form to appear on the back of 20 London buses throughout August (I'm not sure which routes but they're probably based around Hackney). If you see a bus with this ad please take a photo of it and email it to me. The person who sends the highest number of photos of different sightings (no cheating allowed!) wins a small prize, not yet decided.