Ben Kinsella was the 17th teenager to die on London's streets last year, but his murder provoked a wave of anger like no other. Outraged by the senselessness of the killing, and overwhelmed by the feeling that knife crime in the capital was spiralling out of control, hundreds of people took to the streets to demonstrate.

Three days after the 16-year-old was murdered during a night out to celebrate the end of his GCSE exams, some 500 teenagers marched through Islington, north London – where Ben lived and died. The march was organised by his friend Brooke Dunford, who appealed to others on Facebook to join the march. Among them was Brooke Kinsella, Ben's sister and former EastEnders actress.

The group snaked through the streets wearing T-shirts adorned with Ben's face and carrying slogans including "RIP Ben", "You're an Angel" and "Stop Knife Violence". Many chanted for an end to knife violence, but as they approached Shillibeers bar, where Ben had been the night he died, everyone was silent.

In the aftermath of his death, Ben's sister made numerous emotional appeals for her brother's killers to be caught, as did the Birds of a Feather star Linda Robson, whose son, Louis, was Ben's best friend and had cradled him as he died. On 3 July, the three men who murdered Ben were charged.

The family effort clearly impressed the police. Detective Chief Inspector John Macdonald said yesterday: "I am always affected and humbled by the dignity families show in difficult circumstances like this, and the Kinsella family are just the same. For their commitment to the fight against knife crime, I have massive respect for them."

Even before his death, the rising scale of knife crime was not lost on Ben. Soon after he died it emerged that as part of his English GCSE coursework Ben had written to the Prime Minister urging the Government to solve the problem. His letter began: "Youth violence hits deadly peak. When will it stop?" Ben's death also prompted debate about whether it was no longer safe for people to intervene in trouble on the streets. The Mayor of London, Boris Johnson, who lived a few streets away from where Ben was murdered, said he now advised his own children: "Don't get involved, move away."

Meanwhile the police stepped up efforts in Operation Blunt 2, their own fight against knife crime and youth violence. Yesterday the Met arrested more than 200 people across all 32 London boroughs whom they believe are involved in gang-related youth violence.