History
Pimlico is a rare example where a guyed mast remained in use. It has an interesting history other than as a microwave site, but developed as part of the 1956 Backbone plan which proposed a "standby" link from Kelvedon Hatch to join the main route at "Tring". A 1959 network map shows this link as "programmed" and running between Stokenchurch and "Ongar". An un-labelled intermediate point north of London corresponds to Pimlico. A contract was awarded to GEC in 1962 for "Chilterns - Maidstone" - including the link between Kelvedon Hatch and Fairseat. This 2 GHz link was scheduled to be ready for service by July 1964. (2 GHz appears to have been chosen to avoid conflict with the use of the main SHF bands at the other sites).
Pimlico was used, together with Kelvedon Hatch, for the 1965 London Radiophone service. An article in the Post Office Electrical Engineers' Journal in July 1966 gives details of this system for which a number of dipole antennas were added to the mast - see photograph below.
The site features a large building of the standard type but the structure was never replaced: the site existed only as a way to route Backbone traffic across London. The relatively limited number of circuits to be provided could be accmmodated on a single channel with only one dish required for each direction. Backbone closed in 1989 but the site has remained in BT ownership and contiues to carry local SHF links. The main SHF route from London to Birmingham went via Harrow Weald, around 8 miles away.
Antennas for the Hemel Hempstead TV relay were added to the mast in 1969, initially for BBC2. The site was later used for local radio and DAB.
