In the course of a detailed geological examination of the natural stones which have been incorporated into the fabric, and particularly the external fabric, of ecclesiastical buildings in the area of the London Basin, the author has recorded the occurrence of Roman bricks and tiles. The geographical and historical distributions of a number of natural stones that occur within these fabrics have already been described by the author. The rocks of the London Basin are down-folded into a syncline, and the geographical limits of the area of the studies are approximately confined by the geological outcrop of the Upper Cretaceous, Chalk, as shown in FIG. I. These limits reflect a geological area in which natural building stones are not obviously available. None of the typical rocks of the region, customarily clays, sands, and gravels, are sufficiently consolidated, in normal circumstances, to be directly utilised for building purposes. The Romans and others, however, mastered the techniques necessary to convert clay into bricks and tiles, and this paper examines the current distribution, in re-use, of some of these Roman products in the churches of the region. Other re-used Roman materials were, of course, also utilised in church construction. Some of these, such as silcretes, calcareous concretions and travertine, have been reported elsewhere.