The Hells Angels Motorcycle Club is growing at a fantastic rate, with more than 200 chapters - or affiliated gangs - around the globe.

They have a reputation for extreme violence and many police officers believe they have become nothing but a sophisticated criminal network involved in drug trafficking.

To most people in Britain, the Hells Angels are just a throwback to the 1970s and widely regarded as a group of eccentric, ageing bikers who like to fight each other and drink real ale.

So strong is this perception, a veteran London Hells Angel even led a parade of bikers at the Queen's Golden Jubilee procession.

But UK police officers who have investigated biker gangs fear that they represent a significant and growing part of our criminal landscape. They have been alarmed by events in North America.

Mass trials

And it is Canada that has felt the full brunt of biker violence.

Following a rein of terror that shook Montreal for seven years, a huge mafia style mass trial has already convicted scores of Hell's Angels for murder and running a multi-billion dollar cocaine ring.

Montreal's biker war involved 160 murders and more than 200 attempted murders, including the shooting of a well known journalist who had investigated the biker violence.

Despite the convictions, the Hells Angels are still considered the number one drug distribution organisation in Canada.

US police officers and federal agents arrested more than 50 Hells Angels in December 2003, on charges involving gun crime, drug-dealing, violence and extortion.

The arrests, in San Jose, Santa Cruz, San Francisco and other cities across the West followed a two-year undercover investigation by US police officers.

The programme, made with access to US and Canadian gang investigators, follows the rise and rise of the Hell's Angels and their fearsome culture of violence.

It investigates how law enforcement officers struggle against the Hell's Angels sophisticated public relations operation.

Despite the litany of murder, extortion and drug dealing Americans still believe that the Angels are just freedom loving, hard drinking wild men.