SDO14977 - Stabilisation of Embankments & Tunnel, HMP The Verne, Portland, Dorset. Heritage Statement

‘Wessex Archaeology was commissioned by Kier Southern to prepare a heritage statement in relation to proposed stabilisation and repair works at Scheduled Monument HMP The Verne, Portland, Dorset (List Entry 1002411), also known as the Verne Citadel. The Citadel is a large 19th century fort covering 22.6 hectares on top of Verne Hill at the northern end of the Isle of Portland. The interior is a prison, H.M.P. The Verne. The areas of proposed works are mainly located within the northwest corner of the fortress in the vicinity of the north entrance, but also incorporate works to casemates in the south-east corner of the Citadel. The aims of this Study were to provide information on the historical development of the proposed affected areas of the Scheduled Monument, and an assessment of their significance. The Study aimed to provide a preliminary assessment f the impact of the proposed Scheme on the designated heritage assets. The Study has identified that the proposed Scheme has the potential to result in adverse impacts to the historic fabric of elements of the Scheduled. In particular, repair works to the north entrance and tunnel lining, also a Grade II* Listed Building, may entail localised removal and replacement of damaged historic fabric. The original portcullis and its counterweight have been identified as highly significant historic features which remain in their original setting, and which contribute to the significance of both the Grade II* Listed North Entrance, and to the Scheduled Monument as a whole. Removal of the counterweight would result in a substantial adverse effect to these heritage assets. Removal of the modern steel lining from the tunnel would however be seen as a sympathetic restoration. Proposed installation of an ‘umbrella’ structure above the tunnel might result in adverse impacts to original features, including an original gun emplacement, access road and the northern defensive embankment. However there is evidence that the northern half of this area was probably excavated and reinstated in the mid-1970s, indicating the earthworks in this area may not be original. The Study has identified that the masonry wall above the east revetment was constructed between 1909 and 1945, and almost certainly postdates the refacing of the revetment walls, undertaken prior to 1909. Although it has not been possible to pinpoint its precise construction date, the wall is not considered to make a meaningful contribution to the significance of the Scheduled Monument, and it is considered that its proposed removal would not preclude the implementation of the proposed Scheme. On the basis of the above findings, it is suggested that further work may be required by English Heritage and/or the Planning Officer for Dorset County Council in advance of and during the proposed works. A key recommendation is that the proposed repair works to masonry, in particular within the tunnel and north entrance, and to the revetment walls, be designed in consultation with a suitably qualified and experienced conservation architect and/or conservation engineer. Many of the proposed repairs seem to entail potential removal of historic fabric, and it is recommended that design solutions be sought which could avoid or minimise the scope of replacement, where possible. It is recommended that following removal of the sheet steel lining to the tunnel, the tunnel lining should be subject to recording, prior to the removal of any historic fabric. It is recommended that further recording work, possibly comprising a full digital photographic survey, be undertaken in relation to the masonry wall prior to its removal. It is considered that the portcullis could benefit from conservation in situ, and it is strongly recommended that an alternative be sought to the proposed removal and demolition of the counterweight. It is considered likely that much of the land above the tunnel has been removed and reinstated during previous drainage works. However there remains a high potential for in situ elements of the original embankments and access road to survive, especially in the south of this area. It is therefore suggested that an archaeological watching brief should be maintained during excavation of any boreholes and trial holes. It is also recommended that the removal of overburden across this area prior to the installation of the ‘umbrella’ structure be subject to an archaeological watching brief or a controlled topsoil strip. Finally, many of the proposals are still at the design stage with some key details yet to be finalised, and it is considered that the full impact of the Scheme on the significance of the Verne Citadel can in some cases not be fully assessed at this stage. It is therefore considered that a final impact assessment should be carried out, taking into account the precise impacts of the proposed works on the designated heritage assets. The need for, scope and timing, of any further archaeological works should be agreed in consultation with English Heritage. Any works within the Scheduled Monument will require Scheduled Monument Consent.’