History

Initial development of the route between London and Leeds was the subject of contract 23594 dated May 1965 and awarded to GEC. The initial cost was to be £270,000 with a required completion date of July 1966 "or 9 months after receipt of final engineering details or 6 months after completion of all buildings and towers". GEC agreed an RFS date of 1 July 1967. STC's higher bid was rejected, as was one from Marconi for a 4 GHz system at a cost of £454,00. A further contract was awarded to GEC in 1966 for additional channels at a cost of £62,000, for completion by March 1968.

Detail of planned expenditure for 1966 to 1970 shows a total cost of £485,000 for London - Leeds "Radio Links A & B" which was to be two 1800-circuit telephony systems, together with a "protection channel". This figure is likely to include the buildings and towers added specifically for the scheme. Expenditure of £300,000 was forecast for 1967-68, suggesting significant "slippage" from the originally planned date. The addition of a further channel, again a 1800-circuit system, was to cost £70,000 with the main expenditure also in 1967-68. It is therefore likely the A/B/C systems entered service together during 1968. The route south of Carlton Scroop carried links for the Linesman radar system which also became operational around 1967-68.

Most intermediate sites featured a "Standard Tower" - the exceptions were Sibleys where the prototype "Daffodil" design was used and Morborne Hill where an existing steel tower was used initially (replaced by a concrete structure in the early 1970s). Problems with the tower at Farley restricted the capacity of the route initially: the performance of the section between Farley and Upton was found to be poor and there were concerns about the capacity of the structure to accept further antennas. The Standard Tower at Farley was replaced by a one-off design in 1976.

Horn antennas were installed at London and Tinshill when the concrete towers were completed however by the time the London - Leeds route was equipped dishes had become the preferred option and it seems unlikely horns were installed at any intermedate sites. The initial equipment appears to have been GEC type 5558 (Post Office RS 10/21) which was a hybrid transistor/valve design offering six traffic and two protection channels. This equipment was a development of the earlier GEC 5556 (RS 10/15) all-valve design.

The Leeds - London route was established primarily for telephony: television links to Leeds ran via Birmingham and Manchester. A temporary link was provided from Tinshill via Upton in 196? following the collapse of the Emley Moor television mast but later replaced by a direct link from Tinshill. From 1974? the Belmont transmitter was re-assigned to the Yorkshire ITV franchise and a link provided via Upton and Farley. Telephony circuits over the Leeds - London route were migrated to digital links during the 1980s.