History

A route between Birmingham and Bristol appears on a 1959 network diagram as "planned (sites not determined)", running via Wotton-under-Edge. These plans were not progressed until the late 1960s: a document headed "1967/68 PROGRAM WORKS" includes "The provision of two two-way operational channels each of 1800 circuit capacity, and one two-way protection channel between Bristol (Purdown) and Birmingham (Tower)". The document shows total estimated expenditure of £280,000 - with £200,000 in the financial year 1969-70

Two new sites were required at Bredon Hill and Cinderford. The option of routing via Wotton-under-Edge was abandonned, possibly since this would have limited the capacity of the Birmingham and London routes due to the shared section. The route ran directly between Cinderford and Purdown and opened once the new concrete tower at Purdown was available. The two intermediate sites were originally provided with cable stayed masts, limiting the capacity of the route. A 1970s document on trunk network development mentions planning restrictions as a factor impacting the expansion of traffic over the Birmingham - Bristol route, however capacity was increased during the 1980s.

The route was initially established for telephony. The BBC and ITV distribution networks developed with links from London to both cities and and apparently no requirement for a direct route between them. By the 1980s, however, the IBA had a single vision circuit in the Birmingham to Bristol direction - this was connected as a source in the Bristol switching matrix and was a "destination" at the Birmingham end. In practice this allowed one of several sources available at Birmingham to be routed to possible destinations accessed via Bristol. One potential scenario was to allow the HTV local studio at Mold to reach the company's main studios in Cardiff. The BBC also rented a single vision circuit from Birmingham to Cardiff for VHF radio distribution.

Traffic over the Birmingham - Bristol route increased from 1978 onwards with the opening of a satellite "earth station" at Madley. Circuits ran via cable to a new SHF station at Coldwell which was in turn linked to Cinderford. At the time all "external" traffic was routed via London and initially circuits ran south via Purdown to reach the London - Bristol route. This was already heavily used for television links and telephony including circuits from Goonhilly and transatlantic cables landing in Cornwall. When Madley expanded traffic was also sent to Birmingham where alternative routes to London were available.

To allow for the additional traffic from Madley the masts at Bredon Hill and Cinderford were replaced in the 1980s by towers of the "Type 8A" pattern which could accept further dishes. A new site (Bonnylands) provided an alternative route to Birmingham using digital links. Maps of 1980s planned digital show the Birmingham - Bristol link was also migrated. Although Madley remained in operation the site at Coldwell closed in 2004. The SHF network as a whole closed by the late 2000s.