His fellow adventurer agreed. ‘One thing that scared me was the dry bones. Were they donkeys or camels starved of water? Or something else?’

A Gambian and a Nigerian, they were among 560 men I found incarcerated in the Libyan port city of Misrata, categorised not as travellers but criminals for leaving West Africa and trying to reach Europe across the Sahara and the Mediterranean. The accounts of such journeys – the dangers of the desert followed by the perils of the sea – are included not in anthologies of travel writing, but police and immigration authority reports. They tell of torture, rape, despair and a determination to keep going that defies the understanding of the comfortable.