Monitoring took place during the excavation of foundation footings. Photos were taken during the works and of all features and deposits. Features were planned as measured sketches and located onto the clients site plan. The natural substrate, comprising brownish yellow clay with sandstone inclusions, was seen at the base of the foundation trench, between 0.66 m and 1 m below ground level. Demolition and levelling, or ground raising layers overlaid the geology. Two modern brick walls and a modern, subterranean brick structure, with steps were recorded at the northern end of the monitored area. The proximity and similarity in alignment and construction of the two walls 1005 and 1006 to the structure indicates they are associated. A glass vessel recovered from demolition backfill suggests they were demolished or last exposed in the later 20th century. The structure and walls were constructed from bricks stamped with 'Staveley'. These bricks were made by the Staveley Coal and Iron Company at the Campbell Brickworks at Barrow Hill, Staveley from the mid- 1930s (Chapman 2013) until the late 20th century. The bricks at 25 Porter Street appear to include older varieties (Chapman 2013, fig. 5) and are probably reused, making exact dating of the structure difficult. However, the date and construction could indicate it formed part of a semi-sunken shelter, potentially relating to WWII or Cold War activity.
Clare Jackson-Slater (Wed,) studied this question.