A collection of serious academic works by painters, that few had heard of, didn’t seem like the most obvious of crowd pullers. Still, we had a fine exhibition title. American Beauty. And a mighty painting, of the volcano Cotopaxi. We set about building a campaign, including the world’s cheapest TV commercial, which also went viral, around a single dramatic image. And the exhibition, in the Millennium Wing of the National Gallery of Ireland, sold out.