London - Southampton - Rowridge/Ryde

Page last updated: 25/8/2026

History

The London - Southampton route is included on a 1959 map as "Planned (sites not yet determined)" however it appears two intermediate sites were intended. This choice may have been influenced by experience with the earlier London - Isle of Wight TV link. The route would serve as a more suitable replacement, with the potential to carry telephone traffic and to the standard required for 625-line colour television.

The plans progressed, slowly, during the 1960s. The original intention seems to have been for the route to become available on completion of the new London Post Office Tower. All sites were new: ultimately delays in completion of Bagshot impacted the opening of the route. Bagshot also served as the first intermediate site on the London - Bristol route with both routes sharing bandwidth over the first "hop".

Bagshot and Thornhill were both provided with versions of the "Standard Tower" and the standard design of building. A similar tower appears to have been considered for Butser Hill but a one-off design was chosen, adjacent to a radar link site operated by the Ministry of Civil Aviation. This would transfer to the new tower. The Southampton terminal was at Thornhill, approximately four miles east of the city centre, where an existing Repeater Station allowed access to trunk cables.

Contract 23542 was awarded to GEC in November 1962 at an agreed price of £151,882 for a (lower) 6 GHz system. This had risen to a final cost of £260,257 by March 1966. Contract 23562, awarded in December 1963, covered the separate 2 GHz between Thornhill and Rowridge, together with "moving of control point to Western Esplanade [Southampton]". This relates to the decommissioning of the original arrangements for ITV between Ogle Road and Chillerton Down and the creation of a Television Network Switching Centre at the new Repeater Station (SO/E), constructed in the same period. The original price of £40,968 had risen to £88,117 by June 1966.

STC and Marconi had both been invited to tender (for both contracts) but were unable to meet the specifications and did not bid. The initial target date for the main section is not known but the Rowridge section was to be completed by "1st April 1965 subject to receipt of full and final engineering information by 1st March 1964". Further contracts were awarded for additions to the scope - full details are given below. The full system was to be:

A summary of 1960s plans suggests the telephony links would have their own protection channel, potentially creating a "3 + 1" arrangement for vision circuits and "2 + 1" for telephony - requiring a total of seven channels out of the eight available in the L6 GHz band (six if the protection channel was shared between TV and telephony). This is significant since only one (two) channels would then be available at Bagshot for use by the London to Bristol route.

Due to delays at Bagshot the new route would not be available for the planned launch of 625-line television from Rowridge in January 1966. As mitigation a temporary arrangement was agreed. BBC1 and ITV were not available until from Rowridge until December 1969 which may indicate a specific problem with the local 2 GHz link. The main route from London to Thornhill and the TV NSC was made available for testing by the ITA in March 1967.

The developmemt of telephony provision between London and Southampton is unknown however a spur between Thornhill and Ryde was added in the early 1970s - this is understood to have replaced an interim arrangement providing 960 circuits between Portsdown and Ryde. The eventual number of "vision circuits" was higher than might be expected due to the arrangements for Southern Television (later TVS, Meridian) which had main transmitters on the Isle of Wight and at Dover with studios at Southampton and Dover (later Maidstone). This resulted in circuits between Southampton and Dover (Maidstone) via London as well as the normal "network" feed and local transmitter link. Further detail of the television arrangements will be added when analysis has been completed.

The main route between London and Thornhill used horn antennas, a design intended to be suitable for operation on 4 GHz, L6 GHz and potentially on other bands. In practice it appears 4 GHz was used between Bagshot and the Bristol route. We understand 11 GHz digital systems were used on the Bristol route only and the television links to Southampton were migrated to 2 GHz at some stage, however Channel 4 transferred to digital (fibre) links in 1993 and BBC distribution moved to Energis in 1995. The ITV contractor (Meridian) introduced a sub-region for the Thames Valley area in 1993, using the Hannington transmitter and a local news studio in Newbury - this would have required new vision circuits (previously Hannington rebroadcast Rowridge) but it is likely these would have been provided via fibre. The main route from London to Southampton would become redundant once the remaining ITV links had migrated to fibre - however Ofcom data shows BT still operates a 6 GHz link between Thornhill and Rowridge.

Contract Details

[Draft notes at present]

23581 £62,538 in August 1964 (£66,096 at April 1966) and 300517 in August 1966 (£25,000), both for "additional channels". Completion dates requested were 1 March 1968 and 1 July 1968 respectively.