Simon Marcus is co-founder of the Boxing Academy, is a former adviser to the Coalition Government and contested Hampstead and Kilburn at the 2015 election.

The solutions to gang crime are straightforward and proven to work. The problem is that our political establishment, now captured by left-wing ideology, doesn’t want to hear about them. So while politicians remain in denial, the death toll grows.

Sadiq Khan helps to illustrate the problem. In a recent attempt to tackle gang crime he embraced the strategy of Glasgow’s Violence Reduction Unit (VRU), which cut knife crime through a collaborative approach with police, schools, hospitals and other public services.

All well and good. But Khan missed out the other half. Knife crime in Galsgow fell to 40 year lows because Stop and Search reached levels of one in five men, police numbers stayed at all time highs, and arrest levels were higher than in England, as were sentences for repeat offenders. It was this, combined with the VRU, that delivered results.

But that’s out of the question in London. Last year, when Khan suggested a small increase in ‘targeted’ stop and search, he was accused of playing ‘political football’ by David Lammy and rebuked by race campaigners. So, instead, the demanded that the police overhaul their gang crime database or ‘Matrix,’ because 80 per cent of those on it were black, and some were as young as 12.

He shouldn’t have.  Ninety-six per cent of those on the ‘Matrix’ had been sanctioned for a criminal offence – 79 per cent for ‘violence, weapons or robbery.’ Tragically, little has changed since 2003, when Diane Abbott bravely noted that 80 per cent of gun crime in London was black on black. Indeed, a recent freedom of information request showed half of all murder suspects and victims in London are still black, even though the black population of London is only 13 per cent.

Yet many, like Lammy, say that Stop and Search is “dispropportionate” and entertains a “racist fantasy”. He plays a high standard of ‘political football’ too, blaming gang violence on Eastern European mafias and “Tory cuts”. He should know better. Following the riots of 2011, which began on his patch, Stop and Search went through the roof; there were more arrests; longer sentences for repeat offenders, and London saw big falls in crime. These falls were reversed when many of those offenders were let out a year or two later.

Forgetting the lessons of the past is no accident in this case. It arises from a mindset shaped by the leftist ideology that has marched through our institutions. At its root is the Marxist principle that crime is caused by inequality and injustice inherent in the capitalist system. The Equality Trust for example, believes that our violent crime wave is rooted in  ‘inequality, deprivation and massive status anxiety,’ and tells us that ‘we need to admit that every…police officer…prison officer and trauma surgeon with a specialism in treating knife or gunshot wounds is, at root, a measure of our failure as a society.’

University departments produce countless research papers supporting this view, the Guardian newspaper repeats it almost every day and even some police commanders are keen to agree.

This is dangerous, because it apportions moral status based on relative power and social position. The ‘oppressed’ can do no wrong and the ‘oppressor’ can do no right. It also means that criminals have a built-in excuse: to punish them is to blame the victim, and the police are seen as the problem and more public spending the solution.

A simple observation bursts this ideological bubble – namely, that the vast majority of those in poverty commit no crimes at all. In fact, many work very hard to build strong and happy communities and they are not worried about their status.  The link between poverty and crime becomes even less clear when figures show that crime went down during the last recession and that, since then, inequality has fallen, with unemployment at historical lows. Indeed, our current gang crime epidemic has become entrenched during one of the biggest economic booms in history.

The charity sector also enjoyed the good times but, despite a record income of £75 billion last year, it has failed to find the solutions to gang crime. Instead, too many within it still prefer the virtue-signalling explanations of blame, victimhood and race politics.

The Conservative Party is also moving that way, judging by the reaction to Sajid Javid’s recent knife crime announcements. He wanted those who breached their Knife Prevention Orders to face jail. Common sense, you might think. But David Gauke belittled the suggestion: a “Whitehall source” claimed that Javid was “grandstanding on knife crime” and the Howard League for Penal Reform said that he was “playing politics”.

Strangely, Javid’s critics neither acknowledged that knife crime was out of control nor that strong action was required. But it was the tone of derision and refusal to engage that gave the game away. Ad hominem attacks are designed to silence debate and a sure sign of ideological groupthink, which is why almost no one in the Conservative Party defended Javid.

Why would they? When Theresa May was Home Secretary, she managed to cut police numbers, Stop and Search, arrest levels, prison sentences, and violence reduction projects all at the same time. It was a win-win for all the wrong reasons. May gained favour with the Treasury, looked tough on police corruption and signalled her anti-racist credentials. Labour were happy for the police to be clobbered – until crime went through the roof and it became a convenient ‘political football’.

The law courts do their bit, too, and last year 19,634 violent offenders with ten or more previous convictions or cautions avoided jail.  Most of these will re-offend and damage countless lives, but if we are a “failure as a society’”, perhaps we deserve it? We don’t – and nor do the black boys stabbed to death in London, because left-wing ideology has stopped the police from doing their job.

But this is where we are.  While white boys are being saved in Glasgow, a new era of gang crime has become rationalised in London and it will continue until our leaders come to their senses. Yes, we need collaborative approaches, and Stop and Search needs to be accountable. But if you stop the police from doing their job, cut numbers, let violent repeat offenders go free and hide behind dodgy research then don’t ask why crime goes through the roof and the very people you claim to care about are the ones dying.