According to the latest recorded crime figures in England and Wales, there has been a steep rise in violence. Knife offences are up by 21 per cent in the year to September 2017; in London alone the increase is 30.2 per cent — that’s 13,715 incidents.

How should police deal with this disturbing trend? One view is that they need to target likely offenders, especially through an increase in the use of stop and search. However, this has been resisted by human-rights and anti-racism campaigners, who regard the use of such powers as heavy-handed and intrusive. Tottenham MP David Lammy has been particularly vocal, calling stop and search ‘inherently unfair’ because it is used disproportionately to target BME people.

These campaigners claim there is a better way and that we have much to learn from Scotland, where violent crime has been falling for more than a decade. Knife crime there has dropped by 70 per cent in the past ten years and Glasgow, once dubbed ‘the murder capital of Europe’, saw the most dramatic fall of all. Campaigners say Police Scotland has de-emphasised traditional law enforcement in favour of a more ‘progressive and holistic approach’, and has urged us to do the same.

The Guardian praised Police Scotland’s decision to treat knife crime as ‘a public health issue rather than simply a police matter’, concluding that this shows ‘there needs to be a shift in understanding of the root causes of the problem’.

Vice magazine argued that the Scottish experience shows how a ‘radical change in strategy is needed’ while swiping at the ‘get-tough posturing’ of those in England who would bring back stop and search. It cited the words of the acting director of Scotland’s Violence Reduction Unit (VRU), Will Linden, who said: ‘The carrot approach has been much more important than the stick for us in Scotland… the evidence suggests scare tactics don’t work.’

The Mayor of London, who promised to reduce stop and search during his 2015 campaign, has said that he is keen to learn from Scotland’s innovative strategy, which emphasises youth outreach and treats violent crime as if it were a ‘disease’. Sadiq Khan is backed by his Commissioner, Cressida Dick.

The implication in all of this is that prevention and early intervention with vulnerable young people is more effective than traditional law enforcement. We cannot arrest our way out of this problem, is the message.

The true situation in Scotland, however, is different to how it has been portrayed. In 2005, Strathclyde Police created the aforementioned VRU, which was rolled out across Scotland a year later. Over the first five years of its existence, police forces in Scotland actually increased the use of stop and search among forces and brought in harsher punishment for carrying a knife, increasing the sentence from two years to five.

With the merger of the eight police forces into Police Scotland, the number of stops increased further. By 2010, Scotland had four times the rate of stops of England, and crime had gone down. Not quite the liberal approach implied by English commentators.

It is true the VRU was inspired by an innovative approach pioneered in Chicago which brought together the police with other state agencies, including health services, schools and youth centres. They did genuinely important work persuading young people to give up their weapons. But law enforcement underpinned the strategy throughout. There was carrot, but also plenty of stick. It is reasonable to believe that the latter had as much impact as the former.

This is reinforced by what happened next. Just over two years ago, under pressure from campaigners, the Scottish Government introduced legislation to reduce stop and search. Consequently, stops fell by around 90 per cent. Since then, knife crime has started to rise again — by 4.4 per cent in the year ending March last year and by 7 per cent if you include other offensive weapons. While it has not yet reached the levels of the early 2000s, the trend is now upwards.

Perhaps the reason this has not received the attention it deserves is because Police Scotland has been enjoying the public praise being heaped upon it and has not wanted to draw attention to the latest crime figures. Only a few weeks ago, Assistant Chief Constable Mark Williams appeared on the BBC’s Victoria Derbyshire show trumpeting his force’s much vaunted enlightened approach. Police Scotland’s Violence Reduction Board, however, has not been so blasé in private. At a meeting last year, members raised concerns that the recent rise in crimes may in fact have been due to a cut in stop and search.

So, a long period in Scotland where stop and search was widely used coincided with a reduction in knife crime. This was followed by a shorter period in which stops were reduced dramatically and knife crime started rising again.

This same pattern occurred in London. Between 2008 and 2012, an increase in the use of stop and search coincided with a significant reduction in knife offences. But in 2014, the then Home Secretary, Theresa May, announced national reforms to stop and search which would curb its use. Stop and search in the capital declined significantly, and knife crime offences in the capital have been rising ever since.

The correlation is not exact: above a certain level, stop and search can have a diminishing rate of return and start to breach a community’s tolerance level. But below a certain level, it can start to seriously compromise the safety of that community. Interestingly, the reduction of stops in favour of a more ‘intelligence-led’ approach meant that black people were stopped at an even more disproportionate rate than before.

Stop and search has a controversial history and has not always been carried out professionally by individual officers. Liberal–minded people are right to be wary about its overuse. However, it is also regarded by most people as a legitimate and necessary tactic. The advent of body-worn cameras and better training has helped deal with perceptions of trust within communities, especially among ethnic groups. A number of prominent anti-knife crime campaigners, such as Richard Taylor, father of the murdered schoolboy Damilola Taylor, have argued that stop and search — done fairly — is needed. If campaigners want to argue against its use on civil liberties grounds, then they are free to do so, but they have to be prepared to defend the likely effect on crime rates.

Unfortunately, Home Secretary Amber Rudd does not seem interested in confronting the harsh realities of crime, preferring instead to deal in the same platitudes used by others to describe Scotland. She wrote in the Times recently about the government’s forthcoming crime strategy making a ‘step change’ and shifting towards prevention. She went on to say: ‘We cannot solve this problem with law enforcement alone.’

Of course, youth outreach is important and we must offer alternative pathways. But we cannot tackle crime by early intervention alone either. We need law enforcement as the ultimate deterrent to stop irresponsible and rash young people from making mistakes that will harm others and themselves. Put bluntly, we need them to be scared of getting caught and of getting punished.

The idea that the state will enforce the rule of law with vigour and confidence has become deeply unfashionable. The political elite prefers to see criminals as victims in need of therapy and TLC. But it is vital the state fulfils this most basic of functions and it would be better if it did not seem so ashamed about it.

Adjusting to the new reality of crime on the streets, the Metropolitan Police launched a crackdown in November and December called Operation Winter Nights. This led to 900 people being arrested and the recovery of 359 weapons, including 278 knives. Sadiq Khan has just announced that he will support an increase in stop and search in London.

If these initiatives are followed through and crime rates fall again, it may at last encourage a more honest political discussion and give people in authority the confidence to see law enforcement for what it is: a public good, not a societal evil.

Munira Mirza and Shaun Bailey AM debate stop-and-search on The Spectator Podcast.