28th March, 1964
Radio Caroline first broadcasts.

Radio Caroline was the first radio station to broadcast all day in the English language.

Caroline was not the first offshore station; the first ship-based radio station reportedly broadcast in the USA from the casino ship Rex, moored off California in the 1930s. Later, offshore radio ships were anchored off the coasts of Denmark and Sweden in the late 1950s and early 1960s, and since 1960 Radio Veronica had been broadcasting successfully to the Netherlands from a ship off the Dutch coast.

Founded by Ronan O'Rahilly and named after Caroline Kennedy, daughter of John F. Kennedy, Radio Caroline broadcasted from the ex-passenger ferry MV Fredericia, anchored in international waters three miles off the coast of Essex, southeast England. Radio Caroline. The original transmitter power of Radio Caroline (which became Caroline North), was 10 kW, and transmitted on a wavelength announced as 199 metres (which rhymed with "Caroline"), but in reality the station was on 197.3 metres (1520 kHz) at the highest end of the Medium Wave Band next to Radio Luxembourg on 208 metres.

Broadcasting hours were initially limited from 6 a.m. to 6 p.m. daily under the slogan of "Your all day music station", because Radio Luxembourg came on the air in the English language at 6 p.m. and direct competition was avoided. Later the station decided to return to the airwaves after 8 p.m. and it continued until just after midnight. In this way Caroline saved its fuel by avoiding direct competition with the most popular television programmes.

The use of radio sets at work was an uncommon practice and most commuters used public transport. Consequently most of its pop music programmes were aimed at housewives and later in the day they were targeted towards children arriving home from school in the afternoons. Because of the lack of daytime music radio competition during the first six months of transmission, Radio Caroline soon commanded a daytime audience of several million listeners at a time when all-day pop music broadcasting in English was unknown in Europe.