There is an old Chinese proverb which Marcello Di Cintio cites in this charming if somewhat melancholic book on the world’s unneighbourly habit of building walls to keep the ‘other’ out: ‘Everyone pushes a falling fence.’ True, the Berlin Wall did fall down eventually, but pretty much every other piece of passive-aggressive street furniture Di Cintio walks along is still standing. It helps that the author is Canadian, a citizen of the least fenced-off country in the world. He brings a fair-minded, maple-baked sensitivity to the madness of dividing lines and barbed wire, but the effect is all the more saddening. If someone as uncholeric and sweet-tempered as Di Cintio found more despair than hope, it’s not a good sign. Still, he writes well, unpicking some of the world’s trouble spots in spare and lucid prose.

He starts his wall-walking in Western Sahara, and immediately ups the tempo by running a marathon, instituted by the ousted Sahrawis to bring attention to what they say is the Moroccan land grab. On one side of the berm is the Moroccan army, on the other the all-but-hopeless refugees, forever