Use of SHF links across the English Channel was a progression from experiments by the BBC and subsequent ad-hoc use of selected sites for occasional links. By the mid-1950s the Post Office and their counterparts in France had started to develop the details of a permanent link which would be suitable for television and also provide additional telephony capacity. Sites at Tolsford Hill (near Folkestone) and Fiennes (south of Calais) were selected. On the UK side the new station was to be connected to London via an existing cable and so it remained for many years.
The 1960s expansion of the Post Office Network included two intermediate sites within Kent which would link Tolsford Hill to the Post Office Tower. A useful side-effect would be to provide a new link between London and the nearby ITV Southern transmitter at Dover. Tolsford Hill received a new concrete tower in the early 1970s replacing a temporary arrangement which had been required to link with Flimwell and also permitting the expected future expansion of traffic. The original guyed mast from 1959 was by then at full capacity.
From the late 1960s the route ran as follows:
London (BT Tower)
The original 1959 link used a mixture of UK (STC) and French (LMT) equipment operating on 4 GHz to an agreed common standard. Conversion between the UK and French television standards was carried out at Tolsford Hill. It is possible this continued to be used, with modifications, for many years. A BT list of equipment shows Thompson CSF equipment (designated RS 10/58) introduced around 1985 also on 4 GHz for a cross-channel link.
In the 1980s expansion of the BT network two new sites were built in Kent for a further link – this time running between Archers Court (Dover) and Boulogne. This is listed by BT as using Thompson CSF equipment at 11 GHz, 140 Mbit/s and entering service in 1986. The new link has been traced back to a site share at Westley Heights (near Basilidon) – it is not known whether the connection to the main BT network would have been via fibre or a further SHF link via an existing site. The links within the UK were almost certainly also 11 GHz digital.
This second London to France route was