This paper presents a summary of some of the scientific and engineering contributions of Prof. D.B. Spalding up to the present time. Starting from early work on combustion, and his unique work in mass transfer theory, Spalding's unpublished "unified theory" is described briefly. Subsequent to this, developments in algorithms by the Imperial College group led to the birth of modern computational fluid dynamics, including the well-known SIMPLE algorithm. Developments in combustion, multi-phase flow and turbulence modelling are also described. Finally, a number of academic and industrial applications of computational fluid dynamics and heat transfer applications considered in subsequent years are mentioned. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.