The site and buildings were taken over in 1975 by the Foreign and Commonwealth Office's Communications Engineering Department (still better known by its previous name, the Diplomatic Wireless Service), who installed a 50-kW medium-wave broadcast transmitter.

[3] Following successful tests and the installation of further transmitters, from 1978 the site shared responsibility for the BBC's medium-wave services to Europe which had been provided since the Second World War by an FCO transmitting station at Crowborough in Sussex.

From 1987 and into the 1990s, the channel carried a tailored service, branded BBC 648, in which some French and German programmes were interwoven with the main output in English.

[8][9] In July 2001, the Dutch station Radio Nationaal hired the 1296 transmitter to beam its signal to its target audience in the Netherlands and Belgium.

Between 2003 and 2012, BBC World Service used Orfordness on 1296 kHz at limited times of the day for transmissions using the DRM digital radio system.

The final transmission from Orfordness (on either frequency) was a farewell 24-hour broadcast by Radio Netherlands on 10–11 May 2012, marking the end of its Dutch service.

Prior to selling the site to Cobra Mist Ltd, Babcock removed all transmitter equipment, although as of August 2016 all three aerial systems were still standing.

The original 50 kW transmitter (a Continental Electronics type 317), installed at Orfordness in 1975 and used for the station's initial tests, was brought back into service following the major storm that hit southern England during the night of 15-16 October 1987, which cut the main electricity supply to the site.

The directional aerial for 648 kHz (erected in 1981-82) consists of a row of five 106.7 metre (350 ft) freestanding steel lattice towers of triangular cross section, insulated at their base.

It was beamed at 96 degrees (i.e. east) and was originally mainly intended for night-time (skywave) coverage of Poland, Czechoslovakia, Hungary and the western USSR, key target areas for the BBC during the Cold War.

Both the 648 and 1296 directional aerials have limited radiation to the west, meaning that, despite the high power of the transmitters, reception of Orfordness within the UK was poor or non-existent, with the notable exception of parts of south-east England (including London) and East Anglia.

There is also a back-up omni-directional mast radiator for 648 kHz, erected in 1983, which can only handle transmitter powers of up to 250 kW and was used when maintenance work was being carried out on the directional antenna.