History

The route between Bristol and Plymouth via Exeter was originally developed for Westward Television which launched in April 1961. The ITV network feed ran from London to Bristol by cable, this was extended to the Westward studios at Plymouth via a new SHF link and then from Plymouth to the local transmitter at Caradon Hill. Another SHF link ran back Exeter (Whitestone) with a spur to feed the transmitter at Stockland Hill. At this stage there was no return circuit to the ITV network.

Contract 21873 was awarded to Marconi in September 1959 for a 4 GHz system at an original price of £92,581. A bid of £118,021 from STC was rejected; GEC were "unable to offer equipment precisely in accordance with requirements". The requirement was for the system to be "ready and in operation by 30th Jan 1961 or 3 mths from the date when buildings and towers are sufficiently completed to enable the installation to proceed unhindered". Although no detail is given, it seems there were problems with the system as a note dated January 1965 records: "... the contractor is still trying to bring the system up to the specification. Completion is hoped for by August 1965." The cost had risen to £172,018 by September 1966 however this may have included additional provision, see below. The original system used Marconi HM 500 (all-valve) equipment, designated RS 10/12.

All sites were provided with the standard building and towers of a "pyramid" style. Those at Purdown and Forder Battery were subsequently modified and Purdown was replaced by the current concrete tower in the 1970s. Expansion of the route was driven by the need for telephony and television links for the Satellite Earth Station at Goonhilly. This involved a short extension between Forder Battery and Goonhilly and the provision of additional channels over the route from Bristol. In June 1964 contract 23571 was awarded to Marconi for additional channels at a cost of £75,000.

Subsequent development included the award of contract 23588 to STC in December 1964 for a U6 GHz system priced at £177,246 and contract 300516 in August 1966 for further channels costing £64,000.This latter expansion was required by December 1968. GEC had bid for the U6 GHz system but was unable to meet the required date.

Estimates of expenditure from 1966 to 1970 refer to plans for "Radio Link C" - a 960-circuit system with protection channel - and a return channel from Plymouth to Bristol for the ITA. A further one-way link between Bristol and Plymouth, with spurs to the TV transmitters was also planned. This may reflect the need for new links to 625-line colour standard or a desire to replace the Marconi equipment with a type more suited to expansion. Additional telephony requirements were for Bristol - Exeter and Exeter - Plymouth links (960 circuits and conversion of the existing switching system to control the two sections separately) and two additional channels (each 960 circuits) "for Satellite Scheme" which were to be added in separate phases.

Diagram E5017 "Satellite Basic Phase Diagram" shows the STC U6 GHz system was the primary provision over the Bristol - Plymouth section with the Marconi 4 GHz system as standby. Further expansion of television, with BBC and ITV requiring circuits to 625-line colour standard, eventually for four programmes, plus return links to London, plus expansion of interational telephone (and television) traffic via Goonhilly and domestic circuits beyond Bristol, would have required further channels to be added.