On the Southern side of Portsdown at the end of the former service road (Hillsea Road) there are 2 compounds about 70 yards apart; this is the western one. This photo was taken on top of the portal looking south towards Portsmouth Harbour.

This is the south eastern portal  which gives access for servicing and maintenance of the oil fuel reservoirs.

Close up shot of the the portal shown above. The entire site is heavily protected by chain-link fence and razor wire.

Valve compound on top of Portsdown, in North South alignment with Northern and Southern compounds. There are 3 structures in it. In the foreground is a large valve. In mid ground is a brick plinth, which is possibly  the telephone access pit.

Further back is a concrete building which provides access to the underground pumping station..

Close-up of the concrete structure, with its substantial steel door. Inside a stairway leads down to the tunnel complex. To the East of this site is a huge  plateau of spoil excavated from the Fuel Bunkers. 

View of the Northern side portal. In the background can be seen the plateau of spoil generated from the tunnel construction, and which houses the Valve Compound. This site is itself built on a second huge spoil heap plateau  which covers several acres, and rises to 40 feet in places.

Close-up of the Northern portal. There is no road access to this site anymore. This portal probably had no operational use (other than as a ventilation adit), but was used during  tunnel construction as a working tunnel to remove the spoil.

NEW - 15-05-2004

This is a mid 1930s photograph of Horsea House on Horsea Island in Portsmouth Harbour looking north west. Of more interest is Portsdown in the background. Breaking the skyline on the extreme right is Fort Southwick and underneath it the Victorian chalk spoilheap produced during the building of the Palmerston Forts. To the left of this is a large chalk scar indicating that the fuel bunkers are under construction.

Contributor: John Wood