Ver en Cuevana. For the first time in 40 years African skies resound to the roar of a flying boat. Alexander Frater boards a wartime Catalina in search of the romance and adventure of Imperial Airways' legendary route from Cairo to the Cape - down the White Nile to the Rift Valley lakes of Kenya and on to the astonishing Ilha de Mocambique - the forgotten jewel of the Indian Ocean.