Site Records

Site Name: Plymouth Maritime Headquarters
                    (Mount Wise)

Richmond Walk
Mount Wise
Plymouth, Devon
OS Grid Ref: SX458540

Sub Brit site visit 13th December 2004

[Source: Bob Jenner]

At Mount Wise this resulted in the construction of a series of underground tunnels beneath the lawn of Admiralty House by 695th Artisan Works, 172nd & 178th Tunnelling Companies, RE and 99th & 828th Pioneer Companies, PC.

Blasting began on 15th December 1942 (disturbing the C in C in the adjacent Admiralty House) however technical problems and some minor subsidence of the Admiralty House lawn, temporarily stopped work during March 1943. Work was recommenced on construction and fitting out until the spring of 1944 when the tunnels finally became available.

Photo:Some of the galleries in the PUE are high - this one is at least 18' high and is partitioned into several 'rooms' with brick walls.
Photo by Nick Catford

Known as the Plymouth Underground Extension (PUE) it held radio, telephone, telegraph and voice frequency (vf) terminals connected to, among others:

  Army Command and District HQ's  
  Adjacent US Army/Navy HQ's  
  Surrounding naval Sub HQ's  
  Combined HQ's Portsmouth/Western Approaches  
  RAF Command & Group HQ's  
  RAF SW & NW Switching Centres  
  Trafalgar & Rotunda SAC exchanges in London  
  Government Communications Centres at Cheltenham/Bletchley Park  
  US Transportation Centre, Plymouth  
  SW Airfields, Radar & Radios Stations  
  City & County Police/Fire/Civil Defence Controls  

Plan of the Plymouth Underground Extension
Drawn by Nick Catford

A period service Telephone Exchange (not Mounr Wise)
Following the successful Invasion of Europe and the cessation of hostilities the main
Bunker continued as HQ C in C Plymouth.At the end of the war, No 15 Group, RAF Coastal Command was disbanded on 1st April
1945 and when the second and last C in C, Western Approaches, Admiral Sir Max Horton retired on 15th August 1945. Western Approaches ceased to exist as a separate command with the function, if not the title, returning to the C in C Plymouth. The Tactical School also closed.

On 4th April 1949 NATO was formed, one result of which, was the UK, C in C, Plymouth. becoming double hatted as NATO, C in C, Eastern Atlantic. Which roughly corresponded to the old western approaches area.

In 1951, while the C in C, Plymouth and his staff were fully occupied implementing the new NATO commitments, Captain G Roberts. RN, the officer responsible for the setting up and running of the Western Approaches Tactical School at Exchange Buildings, adjacent to Derby House, was sent for, to evaluate, update and re-organise the Mount Wise HQ, now entitled 'Maritime HQ, for its new expanded duties.

In 1955 some blast protection was added to the entrances and ventilators.

From 1951 to at least 1961, Mount Wise, was HQ of C in C Plymouth in both of his roles and contained the following elements:

Joint Operations Room
Upper Floor (glass fronted cabins)

  • Flag Officer/Chief of Staff
  • Air Officer Commanding/Senior Air Staff Officer

Lower floor

  • Naval & Air plotting tables
  • Naval State Boards Air State Boards
  • Convoys Aircraft Availability
  • Independents Aircraft Task Board
  • Enemy Submarines
  • Own Naval Forces
  • Task Force Organisation
  • Duty Naval Commander With Switchboard with direct communications to
    Adjacent MHQ's each local sub area command and
    all RAF radar stations in area.
  • RAF Controller Direct communications to AOC/SASO. Group Captain 15 Group. Joint Intelligence Section, MET Officer. Duty Signals Officer and main floor of Joint Ops Room.


  • Intelligence Office
  • Naval Records Section To log and file incoming/outgoing operational information
    Air Records Section As above
  • Shipping Section: 1) Shipping Room 2) Shipping Movements and records room. To liaise with civilian and military authorities to Provide up to date picture of Merchant Shipping
  • Mine Counter Measures
  • Operations Room
  • Civil Defence Section - provides general picture of civil defence situation in are/sub area
    and to keep shipping informed of fallout conditions
  • Meteorological Section
  • Communications Section Provided joint signals facilities
Illustration of a typical joint operations room in a Maritime Headquarters

Photo:The map in the Maritime Rescue Co-ordination Centre (MRCC) in 1955 (this may be at Mount Wise or Mountbatten) - compare this with the cut down version of the map at Mount Wise (below) that was still in place in 2004

The roof of the MHQ provided an aerial farm for many antennae and a direct microwave link
to the naval wireless station at Fort Staddon.

The location and manning of the Intelligence Office raised several problems, not the least of which was the shortage of experienced officers for intelligence work. With the authority of the Admiralty, Roberts recruited RN Volunteer (Special) Reserve [RNV(S)R] officers with war experience together with senior and junior rates to provide a fully trained staff to man the HQ during any emergency, resulting in Roberts being appointed 'Captain RNR' in charge of Maritime Headquarters Reserve, HMS Vivid.

The Joint Operations Room in 2004 - note the similarity to the MRCC. Photo by Nick Catford (click to enlarge)

For further information and pictures of Mount Wise click here

[Source: Bob Jenner]

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