Pirate radio is thriving in the UK because broadcasters are not providing a wide enough range of music, according to research by media regulator Ofcom.
One of Lenny Henry's characters was pirate DJ Delbert Wilkins
It says up to 16% of adults are tuning in to pirates because of "unique music content" and "super-local relevance".
About 150 illegal radio stations are operating in the UK, with more than half based in London.
Ofcom is to launch a study into tackling pirate stations, whose signals can affect the emergency services.
"The perception of both listeners and broadcasters involved in illegal broadcasting is that the licensed broadcasters are failing to cater sufficiently for the needs of the public," says Ofcom, in a report into illegal broadcasting in the UK.
"Illegal radio is regarded by many as the best place to hear new music, and the best place to hear urban music, DJ-ing and MC-ing in general.
"Illegal stations are also appreciated for their super-local relevance, which often takes the form of information and advertisements about local community events, businesses and nightclubs."
But Ofcom warns that pirate stations are starving legitimate radio stations of audiences, advertisers and money.
Early pirate stations were based at sea due to a broadcasting loophole
The watchdog found that 30% of radio listeners think their programmes have been affected by interference from other stations and broadcasters.
"Of those who suffer interference, 14% believe it is caused by illegal broadcasters," it says. In London, the figure rises to 27%.
According to Ofcom's research, more than 40% of people will switch to another station when interference occurs, robbing legitimate broadcasters of their audience and, in turn, advertising revenue.
But people who listen to pirate radio tend not to be concerned about the problem - which can also affect radio communications by emergency services and air traffic control.
"Many listeners take the view that such claims are propaganda disseminated by the authorities in a bid to control media ownership," says Ofcom.
However, only 2% of people who say they have experienced interference have ever lodged a complaint.