History

The London to Norwich route developed from the link for Anglia Television which entered service in October 1959. Contract 21832 was awarded to Marconi in February 1958 at an original value of £39,510. Bids from STC of £48,856 "not technically satisfactory" and from GEC of £54,271 were rejected - however the final cost in September 1963 had risen to £67,853.

The requirement was "The radio relay system is to provide two unidirectional channels in continuous service, having two separate baseband inputs and outputs and using four of the radio frequencies in one of the following bands [2 GHz or 4 GHz]. The system will comprise two terminal stations, and three repeater stations at Ongar, Sibleys and Ousden." These intermediate sites were later known as Kelvedon Hatch, Sibleys and Wickhambrook respectively. This route would have been sufficient to reach the ITA transmitter at Mendlesham, however it seems the initial contract did not include the two-way link between Mendlesham and Norwich which was needed to allow locally-originated programmes to access the transmitter - this may account for the significant increase in cost.

It is believed the link operated on 2 GHz using Marconi HM200 equipment - Post Office designation RS 9/4. In addition to the three intermediate sites identified in the contract, Mendlesham served as a repeater in the northbound direction with Stoke Holy Cross as the terminal station for Norwich. From there a southbound link was used back to Mendlesham. Anglia, as one of the smaller ITV contractors, was not provided with an outbound "vision circuit" at this stage. The company had ambitions to contribute to the ITV network and had considered funding the circuit themselves but it was to be some years before "...live from Norwich" was technically feasible.

The contract required the link itself to be ready for service by 31 March 1959 with the "supervisory" system completed by 30 June 1959. Both aspects are noted with "actual 27/10/59" - the date broadcasts commenced. Due to the short time available for construction several aspects of the link were of a temporary nature: the three intermediate sites were provided with cable-stayed masts and prefabricated timber buildings. The southern terminal was at Museum exchange, using the tower initially erected for the London - Birmingham 900 MHz link. At Mendlesham the Post Office dishes were added to the ITA mast and at Stoke Holy Cross an interim arrangement used one of the WW2 Chain Home radar towers to carry a passive reflector, with the dish at ground level. By the late 1960s all sites had been provided with new towers although it is understood the three timber buildings were retained.

Subsequent development of the main route was relatively slow - perhaps constrained by the temporary facilities. Contract 23547 was awarded to Marconi in May 1963 for "Alterations" - in practice the transfer of the London teminal from Museum to the Post Office Tower at a cost of around £13,000. This work was completed in April 1966 - delayed from the planned date of July 1964, presumably due to slippage with the main project.

The London - Norwich route carried "Linesman" traffic from the radar site at Neatishead towards the control centre at West Drayton. This was the subject of two contracts: in February 1964 for a temporary link and in January 1965 for the permanent arrangement. This is covered in more detail on the Linesman pages, however the permanent arrangement used the 2 GHz band 1900-2300 not 1790 - 2200. CHECK... with GEC equipment and separate antennas??

Contract 300536 was awarded to STC in September 1967 for a 6 GHz London - Norwich link at a cost of £362,031, however very little detail is known. This may relate to another 1967 proposal for the "Winterton - London Radio Link (960 circuits)" which would have added a new link between Winterton on Sea (connection point for overseas cables) and Stoke Holy Cross, with "addition of one two-way channel between Stoke Holy Cross and London P.O. Tower". A 1974 map of overseas routes shows 900 circuits within the London - Norwich link were reserved for international use, however these appear to have been extended to Winterton on Sea via cable.

The ITA requested a return link from Norwich to London which was included in expenditure plans for 1968-70 at an estimated cost of £155,000. Possibly this was also part of the work contracted to STC - by this stage Marconi had withdrawn from the market. BBC television links to Norwich ran from Birmingham but further expansion over the London - Norwich route occurred from the mid-1970s when the Post Office Research Station transferred from London to Martlesham. A spur was added at Mendlesham, ultimately carrying four vision circuits in each direction. We understand these were used for conference services and experimental broadcasting via satellite.

The addition of Channel 4 required a further circuit from London to Norwich in 1982; Anglia continued to have one vision circuit in each direction.

A diagram showing the links at Mendlesham in the mid-1980s discloses the use of a Pye U6 GHz system for the Martlesham spur, with the links to and from London split between GEC 2 GHz (two channels each way) and U6 GHz systems from Pye and STC (both one channel each way). This may indicate the use of L6 GHz and 4 GHz bands was concentrated on the Leeds route, diverging at Sibleys.

It seems unlikely Norwich or the wider area was expected to produce significant trunk telephone traffic. Some evidence of assumptions about future traffic can be seen in early photos of the London Post Office Tower. In contrast to the other three main routes, only one horn antenna was installed facing north east (towards Kelvedon Hatch) and the section south of Sibleys was shared with the more significant London - Leeds route.