This week 24 years ago on Lavender Hill, about 1,700 people were at a Rockers Reunion concert at Battersea Arts Centre when a feud between two motorbike gangs took a dramatic turn – and ended up in a brutal double murder. The gangs in question were the Hatchet Crew (an Essex chapter of the Hells Angels) and the Outcasts. Their relationship had until then been fairly peaceful – but there were growing tensions about who was the dominant gang, tensions that were about to explode. The Outcasts were gaining members, and and about six months before they had tried to integrate The Lost Tribe gang from Hertfordshire – which would have made them equal in size to the Hells Angels. The Hells Angels responded by making the Lost Tribe honorary members – but by now, American branches of the Hells Angels were pushing the UK side to resist these rival groups.

And an otherwise unremarkable gig in Battersea was where it all came to a head. The event had a good number of Outcast attendees (including some of the security) and it had been going well – until a group of about 40 Hells Angels who had infiltrated the event approached the dancefloor and launched an oganised and brutal attack. The ringleaders reportedly came equipped with microphone headsets and walked through the crowd spotting Outcasts, pointing out targets to the rest of the group.

But while chaos ensued on the dancefloor, the murders would be outside. Keith Armstrong, who had one leg and was known as Flipper, was parking his bike in Theatre Street down the side of Battersea Arts Centre when he was attacked by five or six men with an axe, iron bars, coshes and at least one knife; he was stabbed between four and eight times in the abdomen and left leg, and his lung was punctured. His friend Malcolm St Clair, known as Mal, tried to help, but was heavily outnumbered – so when he was attacked with a hammer and an axe he also collapsed and died on the spot. A witness said that they saw one of his attackers walk off calmly and droving off in a Volvo – so calmly that he even wrote down the number plate. Several others were wounded but survived; Flipper was rushed to hospital, but succumbed to a heart attack that evening.

Witnesses said that the Hells Angels involved in the attack had appeared calm and pleased with what they had done. One of them was heard to say ‘I got the bastard. I got him. I did him.’ And with over 1,000 people at the event, there were plenty of people who had seen what happened (both in the gangs and the general public), and dozens of arrests were made. But there was such fear of retaliation at the time that few dared testify in court, and when the judge declined to anonymity to those who would testify (and in one case, a witness’ identify was accidentally revealed), witnesses quickly faded away, with the cases being dropped. The vice-president of the Essex chapter of the Hells Angels was eventually convicted for organising the attack, and sentenced to 15 years imprisonment, with the judge saying ‘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.’ The prosecution said that the attack was brutal, planned and premeditated – and aimed at making the Hells Angels the main bikers gang in the country. But no one was ever convicted for either of the murders.

The Battersea incident was a dramatic step up in what had until then been a low key turf war, and it kicked off a violent nationwide feud between the gangs that continued for years, with shootings, arson and attacks, backed by an impressive array of weaponry. Nearly a decade later, in 2007 Hells Angel Gerry Tobin would be shot dead on the M40, with seven Outcasts convicted over his murder. For those with an interest in this largely forgotten part of Lavender Hill’s history, Melanie McGrath’s contemporary article Riders on the Storm is a thoughtful and much more detailed account of the fateful night in 1998, and the wider culture of the biker gangs.

But Mal and Flipper are not forgotten, and last week saw a large group of Outcasts, with an impressive set of motorbikes, assemble early on Saturday morning at Battersea Arts Centre to pay tribute to their fallen comrades. The sign post where Mal died always has several small tributes attached to it, and for a few weeks after the anniversary, like every year, it also has a wreath in their memory.