MHG47794 - C.S.O.S. RDF Outstation No.4 Site, Bower


Site of an RDF out-station consisting of a mast within a circular enclosure. Used by the C.S.O.S, part of GCHQ, as a monitoring or listening site.

Type and Period (2)

  • SIGNALS GATHERING STATION (Second World War to 20th Century - 1945 AD? to 1979 AD?)
  • RADIO MAST (Second World War to 20th Century - 1945 AD? to 1979 AD?)

Protected Status

  • None recorded

Full Description

NMRS Report: (08/11/2004)
ND26SW 61.02 23555 62117

Bower C.S.O.S. GCHQ signals Monitoring Station No.4 site at Smerral. This was an RDF out-station consisting of a mast within a circular enclosure. The site is depicted on the OS 1:10560 scale map (1970) and annotated 'masts'.
Information from Defence of Brtain Project form, (Mr A Gutteridge), 1999 <1>.

C.S.O.S. stands for Composite Signals Organisation Station, (known as a "Y" service) which is responsible for monitoring and intercepting radio signals - essentially a listening site. Part of GCHQ - Government Communications Headquarters, which is the centre for Her Majesty's Government's Signal Intelligence (SIGINT). They work closely with MI5 and MI6. The C.S.O.S. was formed by combining of elements of the army, air force, navy and foreign office radio services in the 1950's <2>.

Composite Signals Organisation - A civilian controlled organization created by GCHQ soon after the war in 1947 to direct and rationalize the SIGINT activities of both the Services and the PO. Replaced the Y Service which had operated in a similar role for GC & CS (Government Code & Cipher School). Traditionally GC&CS, and later GCHQ allowed the War Office, Admiralty, Air Ministry, Police and even the GPO to run interception bases on their behalf. With the changes being contemplated that would merge the Service Establishments into a single Ministry of Defence and the pressures of modern technology, GCHQ decided to close down or takeover the majority of such facilities as CSOS during the 1960's. The paramount importance of SATCOM has now reduced the need for a worldwide network of SIGINT sites to a minimum and most have closed since the late 1980's.
The Bower site was probably closed in the 1970's but may still be SABRE-HAARP, 'auroral research'? {SABRE may stand for "Sweden & Britain Radar Experiment" and HAARP is the "High Frequency Active Auroral Research Program" which studies Ionospheric Physics and Radio Science <2>}. There is also another in Brora <3>.

The site was visited by a member of HCAU staff in August 2009. The remains are as depicted on the modern Ordnance Survey map, the site consisting of a small concrete building within a defined hexagonal area, itself within a large circular concrete apron. The anchor points for the mast remain but the mast has gone. <4>

Sources/Archives (4)



Grid reference Centred ND 23555 62117 (45m by 45m) (2 map features)
Map sheet ND26SW
Civil Parish BOWER
Geographical Area CAITHNESS

Finds (0)

Related Monuments/Buildings (0)

Related Investigations/Events (0)

External Links (2)

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