The results of the chemical analysis indicate that the majority of the unknown sherds tested were not manufactured in the Nene Valley and that there is a strong probability that Köln was the major source with only about 16 per cent being attributed to the Nene Valley. The possibility of a further source or sources is also indicated by the sub-group of Köln A. In addition analysis of the Nene Valley control sherds has shown no distinction between the products of Water Newton, Sibson and Stibbington, but some evidence for discrimination in the case of Stanground.
Although Gaulish samian accounts for most of the pottery table-ware found in Britain, Gaul and Germany in the first and second centuries A.D., its repertoire was supplemented by a range of colour-coated drinking vessels. These are generally in different fabrics to those of contemporary samian (ranging from white through to various shades of brown) and are generally finished in a variety of slips, which are usually reduced. The pre-Flavian range of drinking vessels of this kind found in Britain has recently been the subject of a detailed study. Now the colour-coated drinking wares of the later first and second century are beginning to receive attention. During this period the bag-shaped beaker with cornice rim is one of the most popular forms (FIG. I, 1-4) and is frequently found in a fine white paste with a reduced slipped surface. Decoration may be by roughcasting or, particularly from the mid-second century, barbotine or rouletting. During the period concerned (i.e. late first to the end of the second century) vessels of this kind were made at several workshops in Britain, Gaul and Germany. The kilns of the lower Nene Valley, for example, are usually credited with being the source of bag-beakers in a white fabric and decorated with hunting scenes enbarbotine, (often described as Castor ware in earlier British and continental reports after Artis) (FIG. 1, 3-4). However, kilns in Köln produced vessels in a similar form and fabric with roughcast and barbotine decoration (FIG. 1, 1-2) as, it seems, did workshops at Lezoux in Central Gaul and, no doubt, further workshops await discovery.