In recent years much research has been devoted to the question of thermal shock resistance properties of archaeological ceramics and it has become generally accepted that certain shapes (for example, rounded bases) and fabrics (for example, those with grog or calcareous inclusions) are most effective. The evidence from Britain, however, contradicts these theories. A survey of vessels used for cooking reveals that many are flat-based and that size and shape of the rim are of more relevance. Insofar as fabrics are concerned, sandy wares are the most common and choice of clays and inclusions appears to have been dictated largely by geographical proximity to the place of pottery manufacture.