A nine trench evaluation. The scope of the trial trench evaluation was determined based on the perceived archaeological potential of the site. A 3% sample was excavated to target the results of the geophysical survey. A total of eight trenches were proposed (subject to on-site obstructions) and laid out to include appropriate safety buffers around known services. During the works, it was agreed that a further 30m of trenching (Trench 9) would be opened within the northern part of the site within an area previously inaccessible, but which would help to better define the extent of archaeology identified within Trench 1. The location of three trenches were adjusted to avoid services and exclusion zones. These alterations comprised: a 15m-reduction of Trench 4 to avoid a previously unidentified service, a 2m-reduction of Trench 6, and a 20m-reduction, plus movement 2m west, of Trench 5. Within the agreed 10% contingency, part of Trench 1 was boxed to enable archaeology requiring excavation deeper than 1m below ground level to be safely accessed. Trenches were excavated using an appropriately powered mechanical excavator fitted with a toothless bucket under the direct supervision of an archaeologist. Spoil was stored adjacent to, but at a safe distance from the trench edges. Machining continued in even spits down to the top of the undisturbed natural geology or the first archaeological horizon, depending upon which was encountered first. Once archaeological deposits were exposed, further excavation proceeded by hand. The exposed surface was sufficiently cleaned to establish the presence of absence of archaeological remains. A sample of each feature of deposit type, was excavated and recorded, sufficient to resolve the principal aims of the evaluation. The evaluation was able to successfully achieve its aims despite some of the constraints present at the site. It was able to establish that the Roman activity identified to the north and the west partly continues into parts of the site. The density of ditches, quantity of finds and environmental evidence would suggest the edge of Roman settlement activity in the north-west of the site. The results of he evaluation identified two main areas of archaeological remains that warrant further investigation. The concentration of ditches in Trenches 1 and 4, and a possible feature in Trench 9, point to enclosure ditches belonging to rural settlement. The evidence uncovered may relate to activity to the north-west of the site, where evidence in an area now under the current housing estate had previously been identified. Much of the previously unknown evidence was found in the 19th century, or as chance finds or during limited investigations, and therefore our understanding of the development, chronology and character of Roman settlement here continues to be uncertain. The evaluation was also able to identify the remains of the County lunatic Asylum in the form of footpaths and landscaped areas in the south (Fig. 9). Trenches 4 and 5 clearly show the remains of gravel and concrete pathways shown on the historical mapping. The assemblage of ceramic tablewares reused in the modern field drains in Trenches 7 and 8 originate from the asylum and represent a unique and localised pottery assemblage. The evidence relating to the Buckinghamshire County Asylum is of considerable interest. While the footpaths may not require further investigation, the opportunity to recover further examples of the mongrammed tableswares, which were made exclusively for asylum, would merit consideration.
Charlotte Cox (2024) studied this question.