Fort Camden Submarine Mining Establishment (S.M.E.) is believed to have been completed about 1887. The date 1871 is shown on the building adjacent to the Submarine Mining Pier, so it is possible work started much earlier. The plans held in the National Archives are dated 13th June 1888, (WO 78/4300). These show that the Engine Room and Observing Station for the S.M.E.were built between 1885 and 1887
Much of the Station, including the Test Room (Electrical Room), was built in tunnels immediately to the rear of the Pier. The Cable Tanks were located immediately to the right (west) of the pier base. The Gun Cotton Store was built on a higher level to the east of the pier. The Observing Station for the Submarine Mining Establishment can still be seen on the slope above the pier.
Additional background information on Submarine Mining can be seen here.