Following the successful 2015 excavation on top of the Castle mound the project applied for and received a Heritage Lottery Fund grant to excavate again in September 2016. This enabled us to put in two 4x5m trenches that extended the 2015 trench to explore the layout of the buried castle wall we uncovered in 2015. The trenches were large because we knew from last year there is a considerable depth of overburden covering the remains of the castle and their size meant that we could ‘step’ the sides to reduce the risk of collapse.
After removal of the turf and a 20cm layer of topsoil we were faced with demolition material of sandy soil with mixed stone and boulders much like last year. We removed this material to a depth of nearly 1.5m; this limit again determined by safety considerations, but still did not reach a floor level. The bottom of the trench was probed with rods and resistance (a possible surface) was detected about 1.5 deeper than the bottom of the trench. This means that if there is a mediaeval floor at this point it is at least 3m below the current ground surface.
The excavation revealed two substantial walls of similar construction to last year and although somewhat damaged in places they were overall in very good condition. The walls were running parallel to each other, are 2.4m wide and approximately 8m apart, and at right angles to the wall exposed in 2015 which suggests this part of the castle was a square or possibly rectangular structure. This was unexpected because the published information suggests that Oswestry castle was a ‘shell’ Keep, a different type of structure altogether. Also it is likely we are excavating a basement in the interior of the structure which would explain why it is so deep.
The right hand trench (T4, the nearest one in the above photograph) exposed the outer part of the Eastern wall and we were able to excavate this to a depth of 1m. We could not excavate further because this was at the very edge of the trench, but we discovered large well shaped sandstone blocks forming the outer dressed surface of the wall set at an angle of 60 degrees to the vertical. This finding strongly suggests that the structure stood on a substantial splayed base. Because of these findings we are drawn to the conclusion that the parts of the structure we have exposed this year and last year represent a Norman keep or Donjon of probable 12th Century date set on an impressive splayed base.
This was an exciting and unexpected finding that is of significant National importance. This has changed the direction of the research project and provides a rare and important opportunity for further excavations to discover the Keep’s plan and structure more fully. With this is mind we are applying to the Heritage Lottery Fund for a further grant to allow us to excavate on the site for another two years.
The full Precis can be read here