Professor Stephenson is a leading world figure in muscle research. He has made significant and well recognised contributions to our understanding of how muscles contract. His major interest has been in the link between electrical activity in the surface membrane of a muscle fibre and contractile activity, with special emphasis on the role of intracellular calcium. In the course of his research, he has developed techniques that have gained wide acceptance and have been adopted in laboratories throughout the world. He has proposed a novel mechanism for the regulation of muscle contraction that has generated great excitement in the field.