Eggbuckland Keep

Eggbuckland Keep is a defensible keep and one of a series of fortifications built around Plymouth and Devonport in the late 1860s, completed by 1872. It was constructed following the 1859 Royal Commission on the Defences of the United Kingdom, under the direction of Major W.F.D. Jervoise, who supervised Captain Du Cane in its design.

The keep is constructed of slate rubble with limestone dressings and has an earth-covered roof. It is a five-sided, two-storey structure built within a deep depression and surrounded by a wide flat-bottomed rock-cut ditch with a counterscarp wall fronting the main entrance, though a section of the southeast corner of this wall was removed in the late 20th century. Four bomb-proof vaulted chambers, known as caponiers, extend at right angles across the ditch to allow enfilading fire along its length. Originally a drawbridge on the east elevation provided access to a tunnel leading to Forder Battery.

The design employs Free Romanesque style. The main elevation displays a 2:3:3:1:3:3:2 bay arrangement with a central round arch entrance featuring a blast door and stringcourse above a raised datestone inscribed "VR 1872". Above this are blocked rifle-loops in the parapet, flanked by three- and two-light round-headed windows with hoodmoulds. The right side includes square-headed windows below. The exterior features limestone quoins, a weathered plinth, stringcourse, and parapet coping. The east elevation contains a recess for the drawbridge with a roll-moulded round arch and original winching chains, opposite which is a round arch portal providing access to the tunnel to Forder Battery. The four caponiers are single-storey structures with musketry loop-holes in rectangular recesses. Late 20th-century buildings on the keep and a covered bridge on the front are not included in the listing.

The interior is brick vaulted throughout, providing support for floors and roof. The lower floor of the keep contains barrack accommodation along the outer side of a central corridor, with store rooms on the inner side. The upper floor features a large ammunition store with a brick-vaulted lighting passage containing lamp recesses. Access to the four caponiers is via rooms and passages on the lower floor. The upper floor has a similar arrangement of barracks and stores and includes a passage to the drawbridge. Spiral staircases on opposite sides of the building provide access to the floor levels and roof.

Eggbuckland Keep was built as part of a ring of fortifications around Plymouth created in response to the 1859 Royal Commission, which assessed Britain's military defences in light of a perceived threat from France. The Commission's recommendations for Plymouth and Devonport were designed to protect the naval port from land attack in the event of invasion and from seaward attack. Six new coast batteries and a ring of eighteen land forts and batteries, linked by a system of military roads protected by earth banks and cuttings, were constructed to complete the defences by 1872 under Major Jervoise's direction. Eggbuckland Keep was the only fortified keep built on the northeastern section of the defences and, apart from Tregantle in Cornwall on the west side, the only keep constructed. It was intended to serve as a defensible barracks accommodating 230 men with ammunition magazines. The 1859 Royal Commission prompted the construction of approximately seventy forts and batteries across England, representing the largest maritime defence programme since Henry VIII's fortifications of 1539-40. Eggbuckland Keep remains a virtually intact fortified barracks and magazine within the ring of 1859 Royal Commission defences of Plymouth and Devonport.