“As a surgeon who treats people injured in assaults and accidents, the biggest surprise from my research was that the police didn’t know about two thirds of violent incidents which put people in hospital. This is because injured people often don’t report these offences. This startling discovery prompted the now historic meeting in Cardiff in July 1997 of police, local authority and accident and emergency colleagues to pool anonymised information about where and when violence was happening.

Careful testing proved that much more violence could be prevented if prevention is based on information from A and E as well as intelligence available to the police. Violence fell more than 40% in Cardiff compared with 14 similar UK cities. Cardiff became the safest city in its Home Office designated family of cities in 2007. In 2002, violence related attendances at the University Hospital A and E were running at 80 per week. Today, it’s down to 30 per week.

This dramatic decrease is down to sustained, joint effort by police, council and health professionals over two decades, but it’s based on scientific targeting of prevention resources and the use of strategies which have been found to cut violence in cities where they were implemented compared to cities where they weren’t.

But as the years went by, chairing the Cardiff Violence Prevention Board brought to mind some puzzling questions about much wider issues than city safety. Why was it, for example, that we have medical and dental schools in our best universities where new treatments are discovered and tested but no police research centres?

Why were there no similar national institutions for police or probation officers, or, come to that, for school teachers? And why was there a National Institute for health and Care Excellence (NICE) but no similar bodies churning out authoritative guidance for police, teachers and local authorities? And these weren’t academic, “Ivory Tower” questions. As citizens and tax payers, we need to know whether, say, cameras worn by police officers or teaching assistants in schools are effective and worth paying for just like we need to know whether we should have our wisdom teeth out before they give trouble (research shows it isn’t).

The answers often aren’t obvious. For instance, careful testing shows that some seemingly sensible policies, like showing delinquent youngsters the grim reality of prison life, actually increases their chances of offending. “Ecosystem” is perhaps an overused word, but it seemed to me that “evidence ecosystem” is very fitting here. Evidence on what works and what doesn’t needs to be generated – hence the need for high grade testing by university and other researchers.”

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Jonathan Shepherd is professor of oral and maxillofacial surgery and director of the violence research group at Cardiff University; a Fellow of the Learned Society of Wales and the Academy of Medical Sciences; and the independent member of the Cabinet Office What Works Council.