Crossing into Cameroon proved challenging. Aside from the fact that no-one could provide an accurate approximation of travelling time or distance to the border, the road was terrible – really terrible. When unpaved roads in tropical countries aren’t graded to level out the bumps and ensure surface water runs into ditches at the side, heavy rain soon destroys them. Crevasse-deep gullies form between football-sized rocks and the way ahead ends up looking more like a dry mountain river-bed than a road. Such has been the story for much of the past week.