Pirate radio in the United Kingdom has been a popular and enduring radio medium since the 1960s, despite expansions in licensed broadcasting, and the advent of both digital radio and internet radio. Although it peaked throughout the 1960s and again during the 1980s/1990s, it remains in existence today. Having moved from transmitting from ships in the sea to tower blocks across UK towns and cities, in 2009 the UK broadcasting regulator Ofcom estimated more than 150 pirate radio stations were still operating. 1960s Pirate radio in the UK first became widespread in the early 1960s when pop music stations such as Radio Caroline and Radio London started to broadcast on medium wave to the UK from offshore ships or disused sea forts. At the time, these stations were not illegal because they were broadcasting from international waters. The stations were set up by entrepreneurs and music enthusiasts to meet the growing demand for pop and rock music, which was not catered for by BBC Radio services. The first British pirate radio station was Radio Caroline, which started broadcasting from a ship off the Essex coast in 1964. By 1967, ten pirate radio stations were broadcasting to an estimated daily audience of 10-15 million. Influential pirate radio DJs included John Peel, Tony Blackburn, Kenny Everett, Johnnie Walker, Tony Prince, Emperor Rosko, and Spangles Muldoon. The format of this wave of pirate radio was influenced by Radio Luxembourg and American radio stations. Many followed a top-40 format with casual DJs, making UK pirate radio the antithesis of BBC radio at the time. Spurred on by the offshore stations, land-based pirate stations took to the air on medium wave at weekends, such as Radio Free London in 1968. Radio Caroline's audience was one third the size of the BBCs Light Programme in the parts of the country where it could be received, but the Light Programme's audience did not decrease, indicating that pirate radio appealed to an audience that the BBC did not serve. In reaction to the popularity of pirate radio, BBC radio was restructured in 1967, establishing BBC Radio 1, Radio 2, Radio 3 and Radio 4. A number of DJs of the newly formed Radio 1 came from pirate stations. The UK Government also closed the international waters loophole via the Marine Broadcasting Offences Act of 1967, although Radio Caroline would continue to broadcast in various forms right up to