Karl Garside, 45, Simon Turner 41, Dane Garside 42, Malcolm Bull, 53, Dean Taylor 47 and Ian Cameron 46 have been accused of the murder.

Mr Tobin, 35 and a mechanic from Mottingham, London, was killed by a single gunshot wound to the back of the head as he rode his Harley Davidson motorcycle along the motorway after attending the Bull Dog Bash biker festival on August 12 2007.

On the first day of the trial at Birmingham Crown Court today (Monday) it was alleged that on the day of the killing the defendants followed Mr Tobin along the motorway in a car, reaching speeds of up to 90mph.

What allegedly followed was described by Timothy Raggatt QC for the prosecution as a "thoroughly cold-blooded business", carried out "with great skill and precision, great timing and was the product of a great deal of planning".

Mr Raggatt said Tobin was the target of a random attack in "one sense" - suggesting it was his Hells Angels membership, rather than any personal grudge, which had put him in danger.

He said: "This was not the case of a man being killed for any personal motive or any personal reason. This was a man who was targeted not because of who he was but because of what he was.

"In one sense Gerry Tobin was a random victim."

The car suspected to have been used in the shooting was found burnt out later that day but did not provide any forensic evidence.

Mr Raggatt said: "There were contingencies and alternatives that had been planned for. It was in that sense a military-style operation and had at its heart the plain intention to kill."

The six men on trial have also been charged with firearms offences.

Sean Creighton, 44, from Coventry pleaded guilty to the murder and to two firearms charges at a hearing on Thursday.

He will be sentenced at the end of the trial, which is expected to last six weeks.

More than 100 bikers attended the court to hear Creighton's plea - some of whom were members of the Outlaws gang, the main rivals to the Hells Angels.

At the time of his death Mr Tobin's girlfriend of five years Rebecca Smith described him as "a true inspiration to many people" who was "quick-witted" and "charming".

The case continues.

'Man admits murdering biker Gerry...' click here