At the time that the Bill for a proposed new law was first introduced in Parliament in 1966, there were a number of radio stations and proposals for television stations, that were operating outside of British licensing jurisdiction with signals intentionally aimed at British listeners and viewers. Although these extraterritorial stations were marine based in 1966, press reports of similar stations broadcasting from aircraft were in circulation. The Act included the Channel Islands and extended to cover the Isle of Man. As a result of this Act, the offshore stations which had been euphemistically called pirate radio stations prior to the Act then became criminal enterprises if they were operated or assisted in any way by persons who were subject to UK law. At first it was thought by the station operators that if they were staffed, supplied and funded by non-British citizens that they could continue transmissions, but this interpretation proved to be impractical.
The power of the GPO was derived from a series of interlocking legislative acts that began with the Sovereign through Parliament to declare the right to control all communications within the Realm. These powers flowed from handwritten letters delivered by the Post Office, to newspapers, books and their printing presses, the encoding of messages on lines used for the supply of electricity; the electric telegraph, the electric telephone (which was originally deemed to be a variety of electronic Post Office); the electric wireless telegraph and the electric wireless telephone which became known as "telephony" and later as wireless broadcasting (a term that had been out of fashion for years until the advent of the cell phone.) Some of these powers have been relaxed and some of them have been reinforced. An example of relaxation includes the licensing of printing presses as a means of censorship and the reinforcement includes the encoding of messages over the electric power grid following the development of cable television and Internet services via this method of distribution.
In the 1920s the licensing authority of the GPO had been circumvented by the broadcasting of English language programmes directed at the British Isles from transmitters located in several countries within relative proximity to British listeners. The advent of World War II essentially terminated these broadcasts except those of Radio Luxembourg which later resumed commercial transmission.
By the 1960s several companies had been formed in the United Kingdom in the hope that radio broadcasting licenses would soon be issued. At the same time radio monopolies in other adjoining nations had been broken by the establishment of transmitters based outside of national jurisdictions on ships anchored in international waters. The first attempt to broadcast by offshore radio to Britain was made by CNBC, an English language station operating from the same ship as Radio Veronica broadcasting in the Dutch language to the Netherlands. CNBC was not successful and it ended transmissions, but soon press reports followed that a venture called GBLN, The Voice of Slough would be commence transmissions from a ship with sponsored programming already booked and advertised by Herbert W. Armstrong. GBLN was followed by reports that a station called GBOK was attempting to get on the air from yet another ship, with both radio ships to be anchored off south-east England. Many of the people involved in these early ventures were known to each other.
At the same time some of the former commercial television pressure group members had not only registered broadcasting companies, but were working with members of the British Establishment to create well-funded offshore radio stations. The first of these ventures was Project Atlanta in 1963 which had ties to British political leaders, bankers, music industry and Gordon McLendon whose family roots were found in Atlanta, Texas and who had previously assisted Radio Nord to broadcast from a ship anchored in international waters off Sweden. When that radio vessel was legislated off the air by a new Swedish law it became available for use by British broadcasting entrepreneurs. Before Radio Atlanta got on the air the project had become known to other members of the British establishment who in March 1964 were successful in launching their own offshore station called Radio Caroline.
The Texas broadcasting connections to British offshore stations led to Don Pierson of Eastland, Texas in successfully promoting three American radio format stations operating from off the British coastline with considerable transmitting power: Wonderful Radio London or "Big L", Swinging Radio England and Britain Radio. By 1966 many other offshore broadcasting stations had either come on the air transmitting to Scotland, northern and southern England or were in the process of doing so. Press reports included rumours of offshore television stations and the brief success of the Dutch REM Island operation called Radio and TV Noordzee only heightened the fear of the authorities that defacto unregulated broadcasting was becoming so entrenched due to its popularity, that it would not be possible to stop it.
In 1983 Radio Caroline returned to a point off the British shore with a new ship and huge antenna. It was soon joined by Laser 558 aboard another vessel, and while the latter station quickly gained a huge audience, the net effect of the legislation which was continuously tweaked to tighten the noose, plus a sea watch embargo monitoring supplies going out to the Laser 558 vessel, eventually drove its operators into insolvency.
While Radio Caroline managed to return to the airwaves and survive through the 1970s using one vessel that eventually sank in 1980, and then to return yet again with a new ship in 1983, it was primarily an operation conducted with volunteer help. A storm eventually toppled its huge and impressive tower in 1987 and the sea embargo against Laser 558 created more difficulties for Radio Caroline which had limped back on the air with a new antenna system. The Dutch and British governments then raided the Radio Caroline ship and destroyed and removed much of its equipment, but again it limped back on to the air.