Portishead Radio

Portishead Radio (callsign GKA) was a radio station in England that provided worldwide maritime communications and long-range aeronautical communications from 1928 until 2000. It was the world's largest and busiest long-distance HF maritime radio station. In 1974, the station employed 154 radio operators who handled over 20 million words per year. It was originally operated by the General Post Office (GPO), then the Post Office (1969–1981), and subsequently by British Telecom, which was privatised in 1984.

The UK's long-range maritime service commenced from a site at Morgan's Hill, Devizes, Wiltshire, in 1920. In 1925, a remote receiving centre at Highbridge, near Burnham-on-Sea, Somerset, was opened, and in 1928 a transmitting station was opened at Portishead, from which the name "Portishead Radio" was derived.

The main transmitting station, which was remotely operated from the Highbridge site, originally consisted of a large array of radio masts at nearby Portishead Downs. High-power transmitters for the maritime service were operated from a site at Hillmorton, Rugby. By 1936, the station had a staff of 60 radio officers who handled over 3 million words of radio traffic per year.

The station played a vital role during World War II in maintaining communications with the British merchant navy and with patrol aircraft in the North Atlantic. During the war, all communications with ships were one-way in order to avoid revealing the ships' locations to the enemy. The station was short-staffed because many staff were on secondments to various government services, such as operating other radio stations and training new radio officers to work in naval convoys. In 1943, the workload was so great that Royal Navy officers and 18 telegraphists were brought in from (amongst others) HMS Flowerdown, a Naval Shore Wireless Service station near Winchester.

In 1948, the station was expanded again, adding two operating rooms with 32 new radio operator positions, a broadcasting and landline room, and a file of ship and aircraft positions plotted using magnetic indicators on a 36 by 16 ft steel map of the world. Other maps covered the North Atlantic and Western European areas.

During the 1950s and 1960s there was a steady increase in traffic levels, and the telex-over-radio (TOR) system started operations. By 1965, the station employed 86 radio officers who handled over 11 million words of traffic per year, communicating with on average over 1,000 ships per day. Queen Elizabeth II visited the station in 1958.

By 1974, traffic levels reached over 20 million words per year, handled by 154 radio officers. The rise in traffic was driven by demand from the oil market, the deep-water fishing industry, and the leisure boating market. After the Portishead transmitter site closed in 1978, and Dorchester in 1979, the service – still called Portishead Radio – used transmitters at Rugby (Warwickshire), Leafield (Oxfordshire) and Ongar (Essex).

Competition from satellite communications, beginning with Marisat in 1976 later the Inmarsat network, initially had little effect on the station's business, which continued to expand. Following the division of the Post Office in 1981, the station was operated by British Telecommunications. In 1983, a new control centre was opened, adding new radiotelephone and radiotelegraphy consoles, and an automatic radiotelex facility. The transmitter sites at Leafield and Ongar closed around 1990.