Throughout his long and very productive career Amyand David Buckingham, who preferred to go by David, made many important contributions in molecular physics, most especially in the area of intermolecular forces and in the understanding of the electric, magnetic and optical properties of molecules. His work was not only theoretical but also led to the development of experimental methods for measuring various quantities, notably the quadrupole moment of molecules and their hyperpolarizability. With Laurence Barron he pioneered the study of Raman optical activity. His also did pioneering work on the importance of long-range intermolecular forces in determining the structure and properties of clusters.