The Guardian The radicals are pressing for a French Revolution-style solution – a mass execution of the aristocracy Addis Ababa, December 1974: Ethiopia’s Derg leaders, who deposed emperor Haile Selassie in September 1974. Photograph: J. M. Blin/AFP/Getty Images   David Ottaway Addis Ababa, August 23 They are crowded into three long army barracks, sleeping on…