Professor Delbourgo has made important contributions to a wide range of areas in theoretical physics, both in Europe and since coming to Australia. In particle physics in collaboration with Abdus Salam he was one of the leading developers of the use of non compact groups for classifying elementary particles and of the study of non polynomial Langrangian with particular reference to gravitation and chiral theories. More recently he has created a very active group in Hobart studying the non perturbative use of gauge symmetries, the properties of supersymmetric algebra and the dynamics of chaos.