John Anthony Pople has revolutionised the way chemistry is practised today by making it possible to perform chemistry in the computer as a complement to the conventional chemistry of the laboratory. John Pople has been the person most responsible for making computational quantum chemistry usable by the community of chemists at large and has dominated the scene in this area for the past four decades. It is difficult to imagine any significant chemistry department in the world today that does not make use of one or other of the Pople procedures. Australia has benefitted from John Pople's expertise through his numerous extended visits to this country and through his supervision of several Australian PhD students and postdoctoral fellows.