There was originally two guns mounted at this location and it is shown on maps as Harding’s Fort. In 1877 work commenced on the new position which was completed in September 1878. The emplacement was a a sing 12.5-inch 38 Ton, Rifled Muzzle Loader gun. The Magazine was underground immediately below the gun.
In December 1904 plans were filed to upgrade this to a 9.2-inch Breech Loading H.P. Mark 1 which was to be taken from Inchkeith in Scotland. (TNA 78/3656)