The night before Chimamanda Ngozi Adichie won Britain’s prestigious Orange Broadband Prize for fiction, her civil war novel Half of a Yellow Sun was the talk of a group of middle-aged Nigerians thousands of miles away in Arusha, Tanzania.

At the gathering, a Yoruba man from western Nigeria described how the book had moved his wife to talk to him for the first time about her traumatic experiences four decades ago on the other side of the front line, in the eastern secessionist republic of Biafra.