By Ian Youngs BBC News Online entertainment staff

But the music scene would be very different if pirate stations did not exist.

On the face of it, veteran radio disc spinners Tony Blackburn and Dave Lee Travis, who became household names on BBC Radio 1 in the 1960s and 70s, have little in common with urban music bad boys So Solid Crew.

Big breaks on pirate radio

Ms Dynamite (above) Tony Blackburn Dave Lee Travis Kenny Everett Richard Park John Peel Norman Jay Trevor Nelson Judge Jules So Solid Crew

But Blackburn and Travis, now seen as relics of an era when pop music was stuck in a style-free zone, were at the very cutting edge of the music scene when they entered the industry.

As were So Solid Crew, who were among the first superstars to emerge from the UK garage scene, the most ground-breaking home-grown scene since punk.

The connection is that they all made their names on pirate radio stations - which broadcast illegally, but fill the gaps that out-of-touch legal stations ignore.

When Blackburn and Travis joined Radio Caroline in 1964, the station had been on the air for several months and was playing a range of music that did not get on the only legal music station which played any kind of pop music, the BBC Light Programme - the forerunner of Radio 2.

Over the next two years, as the style became more professional, the DJs became more daring and the music became more plugged into national tastes and Radio Caroline was attracting eight million listeners.

Radio Caroline closed in 1968

Other pirates proved popular after starting up in its wake - and had a huge impact on the music scene of the day.

While the pirate stations picked the best songs they could find, when it came to songs from the United States, the BBC preferred to play British cover versions.

So when the pirates played You've Got that Lovin' Feeling by the US group the Righteous Brothers, the BBC played Liverpudlian singer Cilla Black's version, which was released on the same day in 1965.

Pirates' power

The power of the pirates was demonstrated when the Righteous Brothers went to number one and Cilla trailed at number two.

And when a young Welsh singer called Tom Jones arrived on the scene, his first single, It's Not Unusual was considered "too hot for the BBC" - but not for Radio Caroline, which sent it to number one.

DJ Norman Jay was a leading light on Kiss FM

The offshore stations also helped propel The Who, the Moody Blues and Procol Harum, among others, towards the charts - and became too popular for the government and the BBC to ignore.

In 1967, a law was passed that banned the offshore stations and paved the way for the BBC to snatch their best DJs for its new Radio 1, which aimed to capture the style and audiences of the pirates.

As well as Blackburn and Travis, Radio 1 also enlisted former pirates John Peel, Kenny Everett and Ed Stewart.

The station went on to dominate the pop music scene and the DJs became among the biggest entertainers in the country.

Pirate radio carried on in the 1970s, with new reggae and soul stations, and the 1980s saw more boundaries being broken when underground broadcasters moved to fill the gaps not filled by the mainstream.

Inner city stars

In 1985, Kiss FM became the most famous pirate station since Radio Caroline, latching onto the growing craze for house and hip-hop. One of its leading lights was DJ Norman Jay - recently made an MBE - and in 1990 it won a legitimate licence to broadcast in London.

Many transmitters are hidden at the top of tower blocks

When tougher penalties were introduced in the early 1990s, smaller stations with transmitters hidden in tower blocks took over.

A new soundtrack to inner city life, jungle music, gave the pirate radio scene a renewed lease of life, which led to the UK garage boom of the late 90s.

Among the stars of the garage airwaves were the So Solid Crew and Ms Dynamite, who honed their talents on pirate stations before being noticed by the wider world.

Once again, underground broadcasting was the only route for new talent to get exposure, and the stations were quicker to pick up on the new trend than the mainstream.

But when the legitimate stations did notice them, So Solid Crew went on to have a string of top 10 hits and Ms Dynamite won the Mercury Music Prize.

Just as Radio 1 was set up to mimic the pirates in 1967, it gained a sister station in 1Xtra in 2002 with a DJ roster packed with former stars of the underground airwaves.