Radio Caroline was among a number of illegal stations that brought groups like The Rolling Stones and The Who to the UK public.
By Katie Spencer, Arts and Entertainment Correspondent
On this day in 1967, the Marine Broadcasting Offences Act was introduced to stop pirate radio and Radio Caroline was its main target.
But now, 50 years later, radio's rebels are officially going straight - Ofcom has granted the station its first full-time AM broadcast licence.
Back in the 1960s, Radio Caroline was among those stations being illegally broadcast on medium-wave frequencies from ships off the UK coast.
To get Caroline on air a 150ft antenna mast was mounted to a Dutch trawler with one goal in mind - to play pop music all day.
The station's current programme manager DJ Kevin Turner said that, at the time, the BBC was playing "very little" pop music.
He told Sky News: "It was Caroline and the other pirate radio stations that came along that really broke the mould and got people listening to The Rolling Stones, The Who, and Caroline especially pioneered Tamla Motown which had never really been heard in the UK."