The Grand shaft was designed to connect the fort on the Western Heights with the harbour. Its entrance at the foot of the cliffs, off Snargate Street, consisted of a courtyard, gate and associated military guard buildings. A number of phases of development have been identified within the courtyard. A series of major additions and alterations that were made to the entrance courtyard to the Grand Shaft in the mid 19th century constitutes the second phase. One of the additions during this phase was a gas meter room.

This is the only part of the original military buildings which survives largely intact. It belongs to the otherwise destroyed south-west range and stands just outside the tunnel entrance, hard against the cliff face. It consists of a single small room with a concrete floor and internal dimensions of 2.67m (NE-SW) by 2.45m (NW-SE). It is entered through an arched doorway on the north-east side. The black wooden door appears to be of 1970-80s date. Along the top of the doorway is a stepped cornice, the brick work of which needs some re-pointing. The top of the structure is obscured by thick accumulations of soil and vegetation but it appears to have been tunnelled into the cliff rather than being part of the free standing south-west range. Internally the brickwork is generally in good repair and the structure suffers from very little water seepage. The brickwork in all of the buildings associated with the second phase of development of this site used an English Bond set in a moderate cream-yellow sandy mortar with frequent small chalk/lime fragments (2-8mm) and occasional smaller angular flint fragments (2-8mm) (1).

An architects plan of the elevation and sections of the proposed extensions to the entrance structures dates to 1859. This phase of development of the site can therefore be dated to after then (2).

<1> Canterbury Archaeological Trust, 1993, The Dover Grand Shaft Project: Report on Archaeological Work at the Snargate Street Entrance (Unpublished document). SKE6833.

<2> 1859, Historic Plan: Plan, elevation and section of proposed extensions to the (Grand Shaft) entrance structures (Cartographic materials). SKE31699.