Historic seawalls uncovered in Southsea

Structural remains related to 17th century historic defences have been discovered during recent work on Portsmouth City Council’s Southsea Coastal Scheme.

The remains appear to be a wall and possible slipway depicted on 18th century mapping: ‘A plan of the town and fortifications of Portsmouth, with the Blockhouse Fort and the Gunwharfe’ by J.P Desmaretz, dating to 1750.

They were found to the west of Spur Redoubt after being uncovered during a storm swell in December 2020.

Principal Consultant for Wessex Archaeology Alex Godden said: “Mortar samples taken from the structure appear to confirm that it is part of the late 17th century redesign of Portsmouth’s defences.

“The possible slipway may have originally flanked a series of steps to allow access from the defences on to the beach, while the wall’s irregular construction indicates that it was never meant to be seen, unlike the actual defences themselves.”

The remains were found to be directly in the line of upcoming construction works for new sea defences as part of the Southsea Coastal Scheme.

Project Director Guy Mason said: “We had to work quickly, not only to protect the remains during wild weather and tidal conditions, but to provide an alternative to the proposed works.

“After consultation with Historic England and Wessex Archaeology, we came up with the contingency plan to move a section of planned seawall alignment some 2-3m forward in order to preserve the old wall in situ.”

Historic England Inspector of Ancient Monuments Iain Bright said: “These 300 year old remains provide a tangible link to the story of Portsmouth’s historic defences.”

“We’re pleased to have worked successfully with the Southsea Coastal Scheme and Wessex Archaeology to ensure that this discovery is preserved for posterity and that the project continues on track. It’s a positive outcome for all.”

The exposed remains have been surveyed and recorded by Wessex Archaeology, in consultation with Historic England and the Portsmouth City Council archaeological advisor.

The Southsea Coastal Scheme is the UK’s largest local authority-led coastal defences’ project, worth more than £100M. It will stretch for 4.5km from Old Portsmouth to Eastney.

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