Struther Arnott worked tirelessly as a researcher, teacher, leader and maker and implementer of policy in universities in Britain and the USA, always carrying his colleagues along with him through his infectious energy and breadth of academic enthusiasms and values. His outlook was shaped by the stimulus of a broad Scottish education that launched wide interests inside and outside science, including the history and literature of classical civilizations. His early research, with John Monteath Robertson FRS, was into structure determination by X-ray diffraction methods for single crystals, at a time when the full power of computers was just becoming realized for solution of the phase problem. With tenacity and originality, he then extended these approaches to materials that were to a greater or lesser extent disordered and even more difficult to solve because their diffraction patterns were poorer in information content. He brought many problems to definitive and detailed conclusion in a field that had been notable for solutions that were partial or vague, especially with oriented fibres of DNA and RNA but also various polysaccharides and synthetic polymers. His first approach was to use molecular model building in combination with difference Fourier analysis. This was followed later, and to even greater effect, by a computer refinement method that he developed himself and called linkedatom least-squares refinement. This has now been adopted as the standard approach by most serious centres of fibre diffraction analysis throughout the world. After the 10 years in which he consolidated his initial reputation at the Medical Research Council Biophysics Unit at King's College, London, in association with Maurice Wilkins FRS, he moved to Purdue University in the USA, first as Professor of Biology then becoming successively Head of the Department of Biological Sciences and Vice-President for Research and Dean of the Graduate School. As well as continuing his research, he contributed to the transformation of biological sciences at that university and to the development of the university's general management. He finally returned to his roots in Scotland as Principal and Vice-Chancellor of the University of St Andrews, to draw on his now formidable experience of international scholarship and institutional management, to reshape the patterns of academic life and mission to sit more happily and successfully within an environment that had become beset with conflict and change. He achieved this without disturbance to the harmony and wisdom embodied in the venerable traditions of that ancient Scottish yet cosmopolitan university.
