The findings are based on analysis by the London School of Economics of data collected from the West Midlands force after it made a major change in its response model in 2018. It restructured its shift rosters to increase the number of double-crewed patrol cars available at busy times.

With about 2000 response incidents each day, and nearly three years’ worth of incident records, England’s second-largest force provided a huge amount of data for analysis, resulting in three main findings.

1. Double-crewed patrols identify more suspects

   The double-crewed units were more than twice as likely to identify a named suspect than single-crewed units.

   Policing Insight writer Ian Wiggett says officers have long argued that they achieve better results when working in pairs, but until now there has been little evidence.

   Many British forces operate single crewing as a default, and only pair crews at times of specific increased risk. Some deploy a mix of double and single-crewed patrols. In practice, deployment is often determined simply by the nearest available unit.

   Single crewing is also driven by finite resources and response time pressures: doubling up halves the number of units available to respond, which leaves more incidents unresourced for longer. Not all incidents require two officers, so deploying a double-crew unit can represent a waste of resource time.

   However, Wiggett says, when productivity is judged by what the officers achieve from responding to incidents, the improvement in identifying a suspect represents a considerable positive return on the cost of doubling crew size.

   The study conservatively assessed the improvement at 112 per cent and concluded that single crewing more than halved the likelihood of suspects being identified. Conversely, more double-crewed units reduced the overall number of units available to respond.

2. More diverse crews identify more suspects

   Pairing up officers with different profiles secures an even greater improvement in results.

   The study shows that a mix of genders secures a 190 per cent increase in identifying suspects compared with a single-crewed unit. Pairing up an officer with longer service and an officer with less service produces a more than 200 per cent improvement over a single-crewed unit.

   The study, which was only able to access gender, age and seniority data, suggests that a diverse pairing improves interaction with victims and witnesses, or that different officers perceive situations differently.

3. Double-crewed patrols are less likely to be injured

Double crewing reduces the risk of an officer being injured, and considerably reduces the risk of serious injury.

Teams instinctively double crew because they believe it to be safer. The evidence confirms that double crewing reduces the likelihood of injury by around 20 per cent and the likelihood of serious injury by between 80 and 90 per cent.

“It seems obvious that working as a pair should provide greater safety and deterrence against violence, although there is also a view that double-crewed units may be more likely to take on risk,” Wiggett says.

“The data probably supports both theories – double-crewed units are more likely to engage with suspects, but they are also less likely to be injured if an incident becomes violent.”

The West Midlands force response lead, Chief Superintendent Rich North, said most officers would prefer to double crew, mainly driven by feelings of safety. Deploying too many single crews could lead to delays, as officers might have to wait for other units to provide back-up.

In terms of efficiency, not every priority 1 and 2 incident required a double-crewed response – although that was not always evident before an officer got there.

Wiggett says one of the great conundrums of policing is that being productive by identifying more suspects creates more work.

“Being more ‘productive’ in response can cause log-jams elsewhere in the force, and in the wider criminal justice system. But who would argue that it’s not a good thing? And more effective policing should help tackle criminality and reduce problems.”

The West Midlands research was discussed last month during the second annual online Conference on the Economics of Crime and Justice hosted by the London School of Economics and the University of Chicago.