Event/Activity EPM299 - Level 2 Historic Building Record Sally Port Tunnel at Southsea Coastal Scheme Sub Frontage 1, Southsea, Hampshire

Wessex Archaeology undertook an Historic Building Recording of the Sally Port Tunnel on the 25th May 2021, 21st January 2022 and 24th Mary 2022. The tunnel is situated beneath Long Curtain battery and forms part of the Long Curtain, King's Bastion and Spur Redoubt Scheduled Monument which falls within the Old Portsmouth Conservation Area. The monument represents a section of surviving remains of the 17th century town defences. The work was commission by the Eastern Solent Coastal Partnership and formed part of a wider programme of archaeological works undertaken for the Southsea Coastal Defence Scheme project to reduce the risk of coastal flooding and erosion between Old Portsmouth and Eastney. The Sally Port Tunnel falls within Sub Frontage 1 of the scheme. Scheduled Monument Consent was granted to install a new flood gate at the southern entrance to the Sally Port Tunnel to prevent water from Long Curtain moat entering and causing flooding in Old Portsmouth to the north. This work involved the breaking out of existing modern features and fabric including a timber door frame and narrow section of cement render and the drilling of fixing bolts into existing mortar joints. As this work had the potential to expose historic fabric the Historic England Inspector of Ancient Monuments requested that an Historic England Level 2 (descriptive) survey take place prior to the commencement of the works and that an archaeologist was present throughout the breakout and installation works. An initial record of the structure was made on 25th May 2021 prior to the commencement of works to install the flood gate. Monitoring was then undertaken during breakout and installation works on the 21st January 2022 and 24th March 2022 in order to record any exposed fabric. The on-site recording involved the visual inspection and photographic survey of the tunnel and hand measured survey to produce two cross-sections. The recording has provided a description of the tunnel including its composition and character and methods of construction. Several previous repairs and alterations to the structure have also been identified. The breaking out and installation works for the flood gate exposed areas of historic fabric including more of the limestone masonry walls, ceiling and brickwork of the tunnel and entrance chamber.