'Phantom effect' of bobbies on beat cuts crime by a fifth

Telegraph Reporters
Four 15-minute patrols on Tube platforms each day, four days a week, caused a drop in crime - PA

Bobbies on the beat cut crime by a fifth by creating a "phantom effect" when officers are not there, a Cambridge university study has found.

A six-month experiment at 57 London Underground stations found that four 15-minute patrols on the platforms each day, four days a week, caused a drop in crime of 21 per cent.

Almost all of the reduction (97 per cent) was recorded when officers were not actually present, which researchers dubbed the "phantom effect".

The experiment demonstrated the long-lasting effect of short bursts of patrols, said the university team behind it.

Prof Lawrence Sherman, an author of the study, said: "The total crime prevention benefit of police patrols may be greater when they are absent than when they are present.

"We see a huge residual effect of brief appearances by patrolling officers after they leave.

"This phantom effect suggests that crime declines when potential offenders are apprehensive about a possible police presence based on recent patrolling patterns - even when there are no police in the vicinity."

Prof Sherman said the "paradox" could inform a debate on police priorities, "such as the benefits of investigating past crimes compared with the benefits of preventing future crimes".

Platforms in 115 of the most crime-ridden Tube stations, including Russell Square, Oxford Circus and Earl's Court, were chosen. In all, 3,549 calls to police were made from stations without patrols, compared with 2,817 from stations with a sporadic police presence.

They found that crime fell in the entire station almost as much as on platforms, where the patrols were, during the days when officers were deployed.

The researchers are now recommending more patrols to reduce crime.

Dr Barak Ariel, a fellow in experimental criminology, said: "The more that uniformed police have been there, and the more recently, the less likely the future crimes may be to occur.

"If the question is whether proactive patrols do the most good where the most harm is likely to occur, communities might reallocate preventive patrols to locations where we have documented their optimal effects."