The Paulsgrove Chalk Pit

Underground Radio Station

 Created 06-03-2002    Last update 09-02-2007

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During the construction of the Underground Headquarters (UGHQ) under Fort Southwick which acted as the nerve centre for operation Overlord (invasion of Europe), the Army tunnelled into the face of the Paulsgrove chalk pit and built a secure radio station. The purpose of this facility was to act as a transmitting / receiving station for the UGHQ. The idea was to keep the highly visible aerial arrays well away from the UGHQ in case they attracted the attention of the Luftwaffe.  The reason why the actual Radio Station as well as the aerial masts were positioned together was to keep the length of the transmission cable to a minimum thus preserving its efficiency. The distance between Fort Southwick and the Radio Station to the east, is half a mile, and the two would have been linked by secure communications lines.

The entire 172 Tunnelling Company Royal Engineers carried out this work starting in May 1942. They were quartered in the Victoria Barracks (now demolished) at Old Portsmouth, and brought up to the site daily. A section of 179 Company Royal Engineers and a section of 183 Company Royal Engineers (Specialist Well Boring Tunnelling Company) was sent to assist them.  



The main tunnel is 112 feet long, runs from west to east, and contains two chambers separated by a stairway. These chambers have concreted floors. There are two portals; the western one is the main entrance, and the other (eastern) is an escape route. The total tunnel length is 275 feet, which makes it the largest accessible underground work within Portsdown. Twelve feet in from the main portal is a 21 foot long spur tunnel. Parts of the tunnel are lined with the standard colliery style tunnel-liner of the 1940s, which is still in good condition. No other building materials such as bricks were used. A fragment of cable hanger and discarded conduit clips show that electric fittings were once installed, although all service equipment was ripped out long ago. The tunnels were constructed using hand drilling and they are dry and in good condition.

Between the two portals lies a un-connected underground room with its own entrance. 

NEW 09-02-2007
During May of 2003 I recorded an interview for a BBC Radio 4 program about these tunnels. You can download it here. (mp3 format - 1.05MB).

With thanks to Andy Martin for his help with the survey.

 Also Peter Cobb (UK Fortifications Club) and Kevin Miller

 for their contributions


 Don't attempt to enter these tunnels unless you fully

consider the hazards involved.



This is a graphical plan of the tunnels (not to scale). The areas marked in blue are lined. Below is a description of the features. All sizes are in feet. The size column is length / depth, where length is the west / east measurement, and depth is the north south measurement.


Location Size Height Description


Entrance 9 wide 6 Tunnel is 5 feet wide, but entrance is extended to form a gatehouse 5 x 7. Rebate in the chalk doorway suggests secure barrier was fitted. 


Side tunnel 21 x 8 8 Lined  tunnel. Ends in bare chalk.
c The main entrance tunnel 5 x 80 6 Un-lined entrance tunnel. Has 1 foot wide concrete sill running on left floor, from side tunnel to far end. 
d Connecting tunnel 9 x 5 6 Partially lined
e Chamber 1 17 x 8 8 Lined. Concrete floor. Pit, 3 x 1 in northside floor with 6 inch soil pipe terminating.
f Connecting tunnel with stairs going down 7 feet. 26 x 4 6 10 foot concrete stairway leading down. Has the famous "Paulsgrove skull"  carved in the north chalk wall. 6 inch channel runs down floor on north side of stairs.
g Chamber 2 42 x 10 8 Partially lined. Evidence of electrical equipment. 
h Alcove 3 x 3 opening 3 4 foot deep alcove, very rough cut. At the back on the right is a 6 inch borehole leading to up to the surface.
i Connecting tunnel 9 x 5 6 Partially lined.
j Bore hole in roof - - 6 inch bore hole in roof, containing one inch steel conduit leading to the surface.
k Escape tunnel 5 x 62 6 Un-lined. Concrete sills on both sides of the floor, 1 foot wide 2 inches high run the whole length 
m Escape portal 5 wide 2 Partially back-filled. Rebate in outside chalk suggesting strong barrier was fitted.
n Chamber 3 12 x 8 6 Independent chamber, reached by outside path from the western entrance (a). Has slots tight against roof to carry some type of ceiling structure. 

Aerial photo site location    Panoramic photo site location

Grid Ref SU637066

Visit this site - Portsdown Walk No2

long shot of the pounds shelter in the paulsgrove chalkpit

The left arrow shows the main entrance, with the rebate in the doorway. The central arrow points to the independent chamber which is not visible from the ground. The left arrow shows the escape portal. Because the floor of the Chalk Pit has been quarried out since World War Two the portals are now some 40 feet up the cliff face.

west portal of the pounds shelter

Close-up of the east portal, used as an escape route. The rebate for a doorway barrier shows up well. The other portals cannot be easily photographed in close up from ground level.


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