Lewis Wolpert (1929-), embryologist, developed the 'French Flag' model to explain the positioning of cells within parts of developing organisms. He began his research career in soil mechanics. In the late 1950s he switched to biology, completing a PhD on the mechanical properties of the dividing sea urchin egg. Subsequent research at King's College London focused on the movement ofamoebae and development of hydra. As Professor of Biology at Middlesex Hospital Medical School and then University College London, his studies were concerned with the development of the chick limb. He has become well-known for his popular science books, such as The Triumph of the Embryo (1991), for radio and television programmes on aspects of science and for media appearances as a scientist-atheist.