Teddy Bullard has played a leading role in the geophysical drama of our lifetime: the story of plate tectonics. After graduating in physics from Cambridge University and continuing at the Cavendish Laboratory under Rutherford, Teddy was appointed a Demonstrator in Geodesy by Lenox-Conyngham. This resulted in his earliest work, measurements of gravity over the African Rift Valley. Bullard showed that the East African Rift is not a subsidence feature, but instead is a manifestation of the emplacement of dense mantle material close to the surface. Hence Bullard showed that the rift zone was in fact a sundering of the continent. This was significant evidence of convective motions in the earth's interior.