It brought partial closure to one of the most high-profile racially motivated killings in the UK, which became a case study in senseless violence and the system’s inability to deliver justice. Its implications are manifold but among the most serious was the claim the Metropolitan Police was, at the time of the murder investigation, “institutionally racist”. This was the conclusion of the scathing Macpherson report after a public inquiry in 1998.

Officers were described as incompetent and having committed basic errors – they had failed to administer first-aid at the crime scene and didn’t follow obvious leads. Crucially, the prime suspects, who were identified three days after the killing, weren’t arrested until two weeks later. At the public inquiry, the head of the murder squad leading the investigation revealed he wasn’t aware arrests could be made upon “reasonable suspicion” – a basic point of law.

The Met was charged to have suffered a failure of leadership, and the inquiry found the police and the Crown Prosecution Service were affected by issues of race – which had a lasting impact on the Met’s relationships with the black community. Some 70 reforms were recommended but, now, 19 years on, the Met insists it has learned the lessons of Lawrence’s murder and its mishandled investigation. Officers from minority backgrounds now make up nearly 10 per cent of the force, up from 3.4 per cent at the time of the inquiry.

“Race and diversity are vital to the successful delivery of policing services to London. The Met has made huge progress in recent years in providing an improved service to minority communities and continues to work hard to gain their confidence,” a spokesman said.

“We are committed to ensuring the service continues with its recent success in becoming more diverse in its recruitment and having a police service that better represents the society it serves.”

It is not, though, a consensus widely shared. Patrick Jacobs, chairman of Not Another Drop, an organisation that dissuades youth from violent crime, vividly recalls Stephen Lawrence’s murder and the investigation.

“It was life-changing, ground-breaking stuff. It was an open wound that had been left to fester for too long,” Jacobs says. “The murder itself was horrific but the lack of investigation, with everybody knowing who did it – it wasn’t like it was a little secret – we were left thinking, ‘they did it and they’re getting away with it; oh, my God, the police are racist and are covering it up’. It really caused the relationship between police and young black people to deteriorate, which has continued pretty much ever since.”

Jacobs vigorously endorses the Macpherson report, particularly the charge of institutional racism. “I couldn’t think of a better phrase,” he says. “It came from an old, white judge, not some radical black guy. It was an official, academic look at the way police react to and investigate crimes against black youths.”

Jacobs emphasises the disproportionately high number of stops and searches carried out on black youths – a report in 2010 found that a black person was at least six times as likely as a white person to be stopped and searched by police in England and Wales – insisting he has been a searched himself at least 150 times. Although he doesn’t object to police performing their duties, he argues officers don’t take enough care to mitigate the damage they do to their relationships with the young men they search.

“Black kids started to feel, ‘well, there’s no point going to the police’. Imagine the effect of that over years and years,” Jacobs says. “I don’t defend anyone who wants to stab someone. But these kids are getting stopped and searched all the time – they’re completely normalised to it. It’s no longer a big deal at all. If you see a police car go past, you’ll get stopped and searched.

“The police have the right to search people, the problem is how they do it and the damage they do – and then they wonder why these kids don’t want to talk to them when something happens.”

In the week since Dobson and Norris were convicted, there has been a rush, in some quarters, to claim the verdict as proof of the Met’s rehabilitation; a sign it has learned its lessons – indeed, embraced them – and fundamentally altered the conditions that incubated such dysfunction and discrimination. Not even the most ardent protests convince Jacobs. He believes there are well-meaning officers, but that they are powerless to reverse ingrained tendencies.

“I’m not saying they all do a bad job all the time. The specialists who work on things like Operation Trident are specialists who really do their job – it’s the beat cops who cause a lot of the problems,” Jacobs insists.

“They say they’re trying to change but the problem is that some police officers are not nice people. Some people who are in the force shouldn’t be there.

“This can only be the beginning of the beginning. Just because these two guys have been locked up, that doesn’t mean everything is now OK. There are three other guys out there – if the police had done their jobs properly, they wouldn’t be on the streets.”