In a sense, the mere act of setting up an illegal station in defiance of the establishment is a political statement. You might have a pirate station playing wall to wall 1980s hits, but the fact that it is illegal is, in it's own way, an act of rebellion.

However, while you might get away with broadcasting dodgy music for quite some time, history suggests that once the output smacks of any sort of political subversion, the powers that be will come down very heavily.

In the early 1980s in Britain, the London-based pirate station Our Radio was on air for around a year, broadcasting everything from news on the national abortion campaign to Britain's first homosexual radio programme. The authorities paid no heed - until the station broadcast an interview with Danny Morrison of Sinn FΘin. From then on, according to Richard Barbrook, one of the station's founders: "We had the authorities after us every week."

Northern Ireland has had its fair share of political pirate stations, including Radio H Block. More recently, DARC FM broadcast from the south in the late 1990s, calling for freedom of the airwaves.

According to John Hind and Stephen Mosco, authors of Rebel Radio, radio is a highly effective, cheap means of mass communication which can be used by "radical subversives" to incite the public to all manner of politically undesirable behaviour.

While here and in Britain the response from the authorities to political pirates might be to shut them down, in other countries governments behave quite differently. In Colombia, for example, where rebel groups have their own stations, the government has been known either to block or to alter the radio signal - interference which can seriously confuse listeners.

Political pirates may also support pro-government views. An Israeli pirate, Arutz 7, was set up to combat the "negative" liberal and left-wing media. Its right-wing religious stance won so much favour with the Israeli government that in 1999 legislation was passed which made the station legal.

Political pirate stations all over the world act as a medium to voice diverse political opinion. Whether the airwaves should be regulated or not is a political hotbed in its own right with movements such as Free Radio Berkeley advocating "a freeflow of news, information, ideas and cultural and artistic creativity". The station itself was shut down a few years ago, but its mission - summarised as "when your revolution needs a voice" - continues online.