Fort Southwick UGHQ

Overview & History

 Created 25-08-2001   Last update 15-02-2014

Overview & History

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The Discovery - Update - 15-02-2014

I discovered the Fort Southwick UGHQ on Wednesday 14 August 1963 when I was nine years old. I was on a day out with my mum, her sister, and my cousin Jim. We were climbing up the chalk spoil that is directly below Fort Southwick when Jim and I decided to go on ahead of our mums. About halfway up the chalk slope was a roadway running west to east which was partly obscured by undergrowth and protected by a high chainlink fence topped with barbed wire. We spotted a hole in the fence, just about big enough to squeeze through. Now at nine years old this hole looked both attractive and frightening, and as we both crouched there, looking at each other, and wondering what to do, the vast Hand Of Temptation reached out and dragged us in. We were both nervous, and we knew we were doing wrong, so we did not hang about for long: just long enough for me to see The Gate.

Forty eight years later I can still recall the image of The Gate as if I were back in 1963 on that summer’s day adventure. It was a gate made of galvanised steel of square cross section, and a bit bigger than an ordinary door. Behind it there was a tunnel going straight into the hillside which then turned right and out of sight. It was dimly lit by bulkhead lamps on the left wall, and a damp, cold air flowed out like a dark vapour. On the left of the entrance was a bell push. Oh no! Why did there have to be a bell push? The desire to press it was just starting to overcome me when we heard movement from somewhere unseen in the depths of the tunnel; we ran back out through the fence as if pursued by the hounds of hell that we knew were most certainly behind us. It was not until forty years had passed that I learned of what we had stumbled upon: a top secret NATO communications centre and the former WWII UGHQ.

(Extracted from my un-published book – The Portsdown Fuel Bunker).


Fort Southwick

Along the top of Portsdown are five Victorian Forts known as the Palmerston Forts.  Fort Southwick (pronounced Suth-ik) is one of these. Up until 2002, it formed part of an Admiralty Research Establishment, and was used by the DCSA (Defence Communications Services Agency) as a communications fort for the Royal Navy. The Ministry of Defence National Asset Register of 1998 (see links for more info) listed the building as HMS Fort Southwick. All operational use of the Fort ceased in 2002, and during July 2003 it was sold by the MoD to the "Fort Southwick Company Limited".


Under the Fort

During WWII an Underground Headquarters - UGHQ (for operation Overlord) was built beneath Fort Southwick. This provided a bombproof, comprehensive Naval, Army and Air Force Operation Control and Communication Centre - call sign 'MIN'. The headquarters’ main role on D-Day was gathering information and coordinating the Allied naval forces. Reports from radar stations were crossed-referenced with messages from shipping to provide an accurate picture of what was happening in the English Channel. This information was then plotted on a large table map at the Fort, and was passed to the Allied commanders nearby at Southwick House. On the 6 June 1944 there were 700 staff working underground. 

As well as the UGHQ, over 1000 people were based above ground around the fort, at various headquarters associated with the planning for D-Day. These included the army and navy headquarters for the British/Canadian D-Day beaches, Second British Army and the Naval Commander Eastern Task Force respectively. An access ramp was built down into the east ditch (which still exists), where many of these personnel were billeted.

From the very first conference of the Anglo-American Allies held on the 31 December 1941 in Washington DC, the US committed itself to prepare for landings on the European mainland. The Americans feared a Russian collapse and began planning Operation Round-up to invade northern France by April 1943 at the latest. However the British resisted being hasty especially after the disastrous raid on Dieppe in August 1942.  At an Anglo-American strategy conference in Quebec in August 1943 the Allies again agreed to the seaborne invasion of France, now codenamed Operation Overlord, and the Americans insisted that a provisional date of 1 May 1944 be set. 

The underground workings at Fort Southwick were excavated by 172 Tunnelling Company Royal Engineers. Work was started on 16 February 1942, probably as a direct result of the Washington Conference mentioned above, and the complex completed during December 1942. The operation tunnels were about 100 feet beneath the surface. Additional galley facilities were provided in the Central Caponier of Fort Southwick proper. Air conditioning and gas filtration was installed as well as fresh water storage. Access was via 3 notorious staircases from within Fort Southwick - there was no lift. Because of its D-Day connection, its existence was a very closely guarded secret, which still seems to persist even today.  Southwick House located in the village of Southwick a mile north from the Fort, was used as the headquarters for SHAEF (Supreme Headquarters Allied Expeditionary Force) although the actual HQ, on and for some time after D-Day, was a tent in nearby woods.

There is a lot of confusion surrounding the correct name of the tunnel complex which I will try to either sort out or compound here. It has variously been referred to as:

  • Combined Operations Headquarters - COHQ

  • Combined Headquarters - CHQ

  • Underground Headquarters - either UGHQ or UHQ.

COHQ or CHQ should refer to the staff that manned the place, not to the actual location itself. However the Combined Operations part of COHQ is mis-leading because this was a separate military entity which dealt with offensive raids against occupied Europe. CHQ was a generic term used to describe tri-service staffing. The correct term for the command and control centre under Fort Southwick is Underground Headquarters which I have abbreviated to UGHQ.

As part of the Fort Southwick UGHQ construction project, a secure underground radio station was also built in the Paulsgrove Chalk Pit. It was once thought that a tunnel was also constructed linking the UGHQ to the Oil Fuel Reservoir which lies to the west but there is no evidence of this.

Two other back-up UGHQs were built, in case Fort Southwick was put out of action. Some accounts state that the primary one was under Wentworth Golf Course, but it was in fact at HMS Forward  Newhaven. It has been suggested that some functions of the UGHQ were duplicated at Western Heights Dover, although this may just be speculation. Two other forts on Portsdown were also held in reserve, Forts Widley and Purbrook, and some of the telephone poles which connected the 3 forts can still be seen today. 

The UGHQ complex was partly re-used during the Cold War as a Communication Centre. In 1974 a replacement COMMCEN was constructed on the Parade Ground.


Outside the Fort

Below the fort on the southern slope of Portsdown are 3 portals which were used as the emergency exits / ventilation adits for the underground control centre. Two of these (Nos 1 and 2, when counting from West to East) have been sealed-up and covered over, but No 3 (the Eastern most) still exists and has been renovated some time in the mid 1990s. 

A purpose built access road (with un-manned barrier controlled access) leads from the main road to the west of Fort Southwick down to a fenced enclosure which contains the three escape tunnels. Just before the enclosure gate on the left is a ruined brick built structure, possibly a guard post, about 20 feet square. 

The spoil from the underground workings appears to have been tipped straight down the south side of the hill, but is not the case. This prominent Portsmouth landmark is in fact composed of waste chalk generated during the construction of all the Portsdown Forts during the 1860s.

I remember looking down tunnel No 3 when I was 8 years old in the early 1960s. It was secured by a strong galvanised steel gate, and there were bulkhead lights burning all the way along its length. Little did I know then that I was staring into the heart of a NATO comms centre. 


In the late 1990s the underground complex was strengthened and stripped bare. Hampshire County Council expressed interest in purchasing this property from the MOD when it became available, because of its uniqueness and importance during WWII. However because of budget cuts they did not bid for the property when it came up for sale in 2003. Around ten bids for the Fort were received and it was eventually sold to the "Fort Southwick Company Limited". 


Fort Southwick Company Limited

The new owners are full of enthusiasm and there is no doubt that they have the Fort's, and the UGHQ's, best interests at heart. Obviously as a business they have to make a bit from their considerable investment, and this is to be achieved by letting existing post-war buildings to other companies, and by converting the Barrack Block to luxury apartments. They have many plans for the future including some much needed renovations and most importantly public guided tours by:

  • Opening the Central Caponier as a museum depicting the fort's history in the Victorian and WWII eras

  • Exhibiting their collection of Military vehicles on the parade ground

Please note that no part of the fort is open for public viewing and the Fort's owners cannot cater for casual visitors.


UCAP Airsoft

During the latter part of 2006 UCAP Airsoft  leased the UGHQ, installed lighting and removed all the rubbish. They then opened an airsoft facility in January 2007. The guy running the show is Andy Stevens and it is the first time that I have met someone who feels as much empathy for the place as I do. He has told me that he feels privileged just to be in the UGHQ given the world changing events that took place there and no changes will be made other than for Health and Safety reasons. His ambition is to restore the main operations room back to the WWII setting and I will be giving as much assistance as I can with this. He is also opening the UGHQ for public tours by appointment. See the UCAP Airsoft  website for details.


Airsoft in action

UCAP Airsoft in action. The rifles power source is compressed air produced from an internal electric motor. It fires a plastic BB round.

Photo by Andy Stevens


Aerial photo site location     Panoramic photo site location

Google Earth Aerial View

Grid Ref SU628068



plan of the COHQ under Fort Southwick

Layout of the UGHQ underneath Fort Southwick produced by combining the isometric and  normal plans.  It also has the surface features superimposed on it. The thinner north / south tunnels are 'freeways' each 110 yards long to allow un-impeded access through the complex. The east / west tunnels are each 55 yards long. This plan accurately depicts the tunnel layout but some of the floor plan details, especially around the Main Operations Room, do not match what was actually built.

Plans supplied by Geoffrey Ellis of

Friends of HMS Forward


Translation of the original plan mnemonics are shown in blue and were supplied by Peter Cobb - UKFC, and Bob Jenner.

 Notes are shown in [] brackets. Some of the locations stated in this table do no match the actual operational use.

EE1 Western escape route - filled in
EE2 Central escape route - filled in
EE3 Eastern escape route - still exists
1 Water Tank - this is outside the plan at the top left
2 Logistic and ground damage plot
3 Fire Point
4 Logistics
5 DCHQ No 2 - Damage Control HQ
6 Plans
7 Intelligence Office
11 Logistics
12 Intelligence
13 Commander in Chief's Communications Records
14 Technical
15 Intelligence
16 Commander in Chief
17 A/COS (A). A/COS (T) - Assistant Chief of Staff Administration and Assistant Chief of Staff Tactics
18 Submarine & Naval Air Liaison Officers
19 Belgian, French and Netherlands national advisors. Flag office Netherlands (G.B)
20 Records Room [more likely the coding room]
21 Main Operations Room
22 OPS - Operations Office [reported to be the WT room]
23 SOO - Staff Office Operations
24 COAS - [ thought to be Chief of Air Staff but this should be CAS - possibly Chief of Army Staff]
25 A/COS OPS - Assistant Chief of Staff Operations
26 SEC COAS - Secretary to COAS [see 24]
27 Flag Lieutenant
28 Conference Room
29 Maritime Air Liaison Officer
30 Shipping Plans
31 Trade Records
32 Trade plot
33 National Shipping Authority & Military Movements
34 A/COS plans - Assistant Chief of Staff plans
35 COS - Chief of Staff [normally a Rear Admiral and 2nd in command]
36 SEC COS - Secretary to Chief of Staff [see 35]
37 Channel committee secretariat
38 Secretary
39 Spare
40 SOMW - Senior Officer Mine Warfare
41 SONCS (CH) - Senior Officer Naval Control Service
42 SONCS (H) - Senior Officer Naval Control Service
43 A/COS trade - Assistant to Chief of Staff {with responsibility for Trade (Mercantile Marine) see 25}
44 Q Message Room - may be referring to "Q" {or deception i,e, Operation Fortitude} messages. This was one of the duties of the EXTRA rooms and tunnels below parts of the Western Heights  Dover
45 Mine Warfare Plot
46 Mine Records
47 Clock control. Update 02-01-2010: the small "clock room" had racks in it that were full of glass tubes with the small ships in for the map room. (source Andy Stevens)
48 Office 2
49 Typing Pool
50 Top Secret Registry
51 CSO - Command Signals Officer
52 Fire Point
53 Netherlands Crypto Office
54 Crypto Office
55 WT Office - Wireless Telegraphy
56  OPS PBX - Operations - Private Branch Exchange
57 GPO Relay Set & Frame Room
58 GPO Battery Room
59 Meteorological Office
60 Spare
61 Cleaners Store
62 Couriergram Office
63 MSO - Main Signals Office
64 MSO Records  - (see 63)
65 Admin PBX - Administration  - Public Branch Exchange
66 GPO Power Room
67 Crypto Store
68 Crypto Workshop
69 TP Room  - Teleprinter
70 TP Room  - Teleprinter
71 Spare
72 WR Room   - Wardroom Store
73 Wardroom
74 Tube Exchange & TP Teleprinter Store
75 TP Room   - Teleprinter
76 TP Room  - Teleprinter
77 Tube Motors
78 EEM Sub-station  - Electrical Engineering Manager (HM Dockyard system) so not off National Grid but supplied by private Generation Station off Main and Victoria Roads in the Portsmouth Dockyard
79 TP Switchboard  - Teleprinter switchboard [private wire network]
80 Galley
81 Wardroom
82 Spare
83 GPO - (General Post Office)
84 GPO - (General Post Office)
85 GPO V/F Room - Voice Frequency Repeaters  [audio amplifiers]
86 GPO Carrier Room
87 EEM Store  - see 78 above, store for spare parts, cable etc
88 Store
89 Ratings Mess
90 Dormitory
91 Galley Store
92 Dormitory
93 Officers Lavatories
94 Dormitory
95 Dormitory
96 GPO - (General Post Office)
97 Secondary Lighting Batteries
98 AC Room -  Air Conditioning Room {in the 1942/3 meaning of the term}
99 Ratings Lavatories
100 Engineers Workshop
101 Engineers Store
102 Boiler Room
103 DCHQ No 1  (Damage Control HQ)
104 Coke Hold
105 Diesels
106 Coolers
107 Ladies Lavatories
108 Air conditioning plant
109 Police Keyboard
110 'B' adit air intake tunnel
Fort Southwick

(HMS) Fort Southwick, sitting on top of a mile of tunnel complex. England expected a lot out of her in the past and the new owners intend to put a lot back in. The future for the Old Lady looks promising.


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Overview & History


 UGHQ - modern