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 radiotelephony station. In 1974, there were 154 radio operators who handled over 20 million words per year.
The station's control centre, which was based at Highbridge, near Burnham-on-Sea, opened in July 1928. It was constructed by Marconi Wireless Telegraph Company and operated by the General Post Office (GPO). Following the privatisation of the post office in 1981, the station was operated by British Telecommunications PLC (now known as BT Group PLC).
The main transmitting station, which was remotely operated, originally consisted of a large array of radio masts at nearby Portishead Downs; it was replaced by a single radio mast at Clevedon. It was used until 1972. Various other remotely operated transmitting stations, including Devizes, Rugby, Leafield, Chipping Ongar, and Dorchester, were also used.
By 1936, the station had a staff of 60 radio officers who handled over 3 million words of radio traffic per year.
World War II
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 away 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 a Royal Navy officer and 18 telegraphists were brought in from HMS Flowerdown, a Naval Shore Wireless Service station near Winchester.
In 1948, the station was expanded again, adding two new 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.
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 1000 ships per day.
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 deepwater fishing industry, and the leisure boating market.
Competition from satellite communications, which began in the 1980s, initially had little effect on the station's business, which continued to expand. In 1983, a new control centre was opened, adding new radiotelephone and radiotelegraphy consoles, and an automatic radiotelex facility.
By the end of the 1980s, satellite communications had started to take an increasingly large share of the station's business, and a program of severe rationalisation was started, leading to the closure of two transmitting sites at Leafield and Ongar.
Closure and redevelopment of the site
In 1998, British Telecom Maritime Radio Services announced its planned closure of Portishead Radio. The long-range services (HF bands 3-30 MHz) ceased at midnight on 31 August 1999. The short-range VHF maritime band (156-174 MHz) services closed at 12:00 on Sunday 30 April 2000, and the medium-range services (MF maritime band 1.6-3.0 MHz) services at 12:00 on Friday 30 June. The station closed in April 2000.
In September 2004, Sedgemoor District Council adopted a local development plan that included the site of Portishead Radio for future housing development. In October 2007, planning permission for a development of 190 houses and flats on the site was granted, and shortly afterwards the old radio station buildings were demolished.
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