Surface Sites

Portsdown Main

 Created 17-10-2004   Last update 06-08-2019

click the arrow


page 1 of 4


Portsdown Main was an impressive 'art deco' style building which dominated the north Portsmouth skyline and was familiar to any Portsmouth resident who would probably have identified it as ASWE. Its history has been poorly documented due to the nature of the defence work that went on there. 

It was designed in the 1930s (hence its style) as a building which would be located somewhere in the UK. The Second World War prevented further progress and it was eventually built on Portsdown in 1952 as an Admiralty Signals Establishment (ASE). It was subjected to many changes during its lifetime either wholesale or with various departments coming and going. The history of its various forms and predecessors is very controversial. I have received many emails telling me that the list below is inaccurate with conflicting suggestions on how to correct it. The one now shown is final - inaccuracies and all.  

Admiralty Signals Establishment (ASE) 1941 - 1947
  Admiralty Signals and Radar Establishment (ASRE) 1948 - 1959  
Admiralty Surface Weapons Establishment (ASWE) 1959 - 1984
  Admiralty Research Establishment (ARE) 1984 - 1991  
Defence Research Agency (DRA) 1991 - 1995
  Defence Evaluation and Research Agency (DERA) - 1995 - 2001  



There were a total of 32 buildings on the 46 acre site built between 1946 and 1955 with Portsdown Main being the most outstanding. To the west is Fort Southwick a former Royal Navy COMMCEN. To the east are two further distinct sites on Portsdown Technology Park: an operational Ministry of Defence (MoD) establishment consisting of the Maritime Warfare Centre (MWC) and the Land-Based Test Site (LBTS); and QinetiQ Britain's largest independent science and technology company.

Portsdown Main finally closed its gates on 1 January 1997 and although there had been a number of Government departments interested in the site none had any plans to move there. On 3 October 2002 it was announced that the Defence Science and Technology Laboratory (DSTL) - formed by splitting DERA into DSTL and QinetiQ on 2 July 2001 - was going to move back, but this was cancelled in April 2004.

The building was put up for sale on the open market but a buyer was never found and consequently, in April 2010, is was decided that  Portsdown Main was to be demolished. Although it was a significant local landmark the building was unlisted and a structural review revealed that the building was unsound. Demolition was completed during September 2011. Read more here


All the above information is in the Public Domain


Contributors: Mike Dobson, Andrew Taylor, Paul Mayo

Grid Ref SU631068

Google Earth Aerial View

aswe illustration

The front cover illustration from an ASWE recruitment information pack of 1974. The ship is HMS Bristol (D23) the only Type 82 Destroyer to be built. The featured radar is a STIR (Surveillance and Target Indication Radar) manufactured by Marconi with two back-to-back aerials and was to be known as Radar Type 1030 when in naval service.

Source: Andrew Taylor

Photo Interpretation: Dave Spencer (ship)

                                   Paul Mayo (radar)

Portsdown Main Map

 Map 1

This shows the position of Portsdown Main (arrowed) in relation to Fort Southwick to the west and Paulsgrove Chalkpit to the south. The road running along Portsdown at this point, formerly called Military Road, was adopted by Portsmouth City Council in February 1997 and renamed James Callaghan Drive in honour of the former prime minister who was born in the city.

Portsdown Main map

 Map 2

Portsdown Main is arrowed and it can be seen that the building was rectangular with a central quadrangle or light well. The boundary line of Hampshire County Council to the north and Portsmouth City Council to the south runs right through it which made planning applications a nightmare. 

ASRE 1953 Main_Block_West

 1953 looking west. The main block has its steel work in place.

Source: Paul Mayo

ASRE 1954 Main Block South East

 1954 looking south east. The main block begins to take on its familiar shape. Just 57 years later the bulldozers would be here for a very different reason.

Source: Paul Mayo

Portsdown Main - just built - 01

NEW: 06-08-2019

 Portsdown Main shortly after is was built.

Source: Mike Dobson

Portsdown Main - just built - 02

 NEW: 06-08-2019

I could be wrong, but I think this was the cafeteria.

Source: Mike Dobson

LBTS 1985  Main_Block and T23 Mast

1985 - Portsdown Main displays its full glory.

Source: Paul Mayo

Portdown Main from Tescos carpark

 On the right of centre skyline is Portsdown Main a prominent Portsmouth landmark as seen from Tesco's car park at North Harbour. To the west (left) Fort Southwick can be made out and below the building is the  Paulsgrove Chalkpit.

Portsdown Main Demolition 25/09/2011

 25 September 2011 - Tesco's car park. The west wing has gone and the central structure is all but destroyed. The Colonel is the only one still smiling.

Demolition close up

 22 September 2011. The photo (and the sign on the right) speaks for itself.


click the arrow


page 1 of 4