Two men were killed and a third injured in the attack last January.

Judge Geoffrey Grigson told 44-year-old Ronald Wait: "You took an active part in conspiring to cause grievous bodily harm - a conspiracy which led to the death of two men.

"In truth they were executed in a manner that was as ruthless as it was arrogant."

Outside the court, the parents of former soldier David Armstrong, one of the men who died, said they felt no anger and appealed against any revenge attacks.

Bob Armstrong, from Belfast, said: "We would not like anyone from any organisation to go out and seek retribution on his behalf."

David Armstrong's girlfriend, Sue Grimoldby, said she would "like to think the Hell's Angels had a sense of shame".

"But I suspect that is not the case," she added. "Now our son, Scott, will have to grow up without a father."

The prosecution did not press a murder charge against Wait, as the jury failed to agree a verdict after deliberating for nearly four days.

Wait, 44, a father-of-two from Dagenham, Essex, was convicted of conspiring to cause grievous bodily harm.

He had denied the charge and also denied murdering Malcolm St Clair, 35, the other man who died.

The prosecution offered no evidence against Raymond Woodward, who was accused of murdering Mr Armstrong, and Barry Hollingsworth, who was charged with both murders.

Many witnesses either refused or were reluctant to make statements through fear. Both men denied the charges.

Armed attack

Wait - known as "Gut" because of his size - was vice-president of the Essex Chapter, known as the Hatchet Crew.

He told the court that he had been at a clubhouse in Reading on the night of the attack at a Rockers Reunion concert at Battersea Arts Centre in south west London in January.

The prosecution described the attack by the Hells Angels as a "brutal, planned and premeditated" and aimed at members of the Outcasts as part of a battle to become the leading bikers group in the country.

They carried out the attack armed with axes, knives, hammers, coshes and baseball bats.

Mr St Clair was attacked by two Hell's Angels - one wielding an axe and the other a knife. The prosecution had alleged that Wait had the axe.