Edit: For people outside of England, Tesco is one of the bigger or biggest convenience store chains, similar to 7-11. The kids are wearing traditional school uniforms. So it'd be similar to graffiti of American kids in conservative, traditional dress saluting the 7-11 logo.
http://images.google.com/images?q=banksy%20tesco&um=1...
Edit: For people outside of England, Tesco is one of the bigger or biggest convenience store chains, similar to 7-11. The kids are wearing traditional school uniforms. So it'd be similar to graffiti of American kids in conservative, traditional dress saluting the 7-11 logo.