A hundred years ago, photographer Sergei Prokudin-Gorskii travelled around the Russian Empire taking the first colour photographs of a world that was about to be swept away by the Bolshevik Revolution. Using a unique method of colour photography, which he had developed, he managed to capture images previously never seen. Dina Newman speaks to Michel Soussaline, Prokudin-Gorskii's grandson. Photo: Peasant Girls, 1909. Credit: Library of Congress; Famille Procoudine-Gorsky.