Naturally, if data from a large number of boreholes are available (over 4,000 in an example given in the paper for a current investigation in London), it is a relatively straightforward matter to establish a 3D ground model which approaches reality. The authors treat this process well, but tend to overlook the fact that in the great majority of ground investigations carried out globally, useful 3D ground information is a rarity and is commonly absent, especially on remote sites. Access, scale, time and financing often combine to minimize or exclude sub-surface data collection. Mining exploration, where 3D computer models of the ground have been used and developed over the past two or three decades, notably in the Americas, Australia and South Africa, form an exception. Thus, the models of both Fookes (1997), Fookes et al (2000) and Baynes et al. (2005) as well as that of Culshaw (2005) are needed by the profession. It would be appreciated if the authors will acknowledge this in appropriate parts of their text.