What makes a great photograph? Stephen Sackur speaks to one of the great women pioneers of photo journalism, Marilyn Stafford. She was born in the United States but moved to Paris where she became the protégé of the brilliant Henri Cartier-Bresson. Like him, Stafford loved to capture intimate portraits of ordinary people. She has photographed everything from refugees fleeing war to models on the fashion catwalks. Now at 93 her work is being admired by a new generation.