It was an odd spectacle: Us finance minister do not often spend time in African slum and rock stars rarely take part in high-level discussions about development economics. But the trip revealed a few thing about the changing relationships between government, charities and celebrities. Even if politicians in democracies don't have to do what voters want, they generally do take their opinion seriously. So, if charities want them to be nice to Africa, they must persuade voters to demand this. And attract voter' attention, it helps to have a few celebrities.