Tougher prison sentences reduce crime, particularly burglary, according to ground-breaking research.
The study, by academics at Birmingham University, also found that during periods when police detect more offences, crime tends to fall overall, suggesting that levels of police activity - and therefore of staffing - have a direct impact on criminal activity.
The findings are likely to be seized on by critics of the government's plans for reducing the number of police officers as part of spending cuts.
The research, carried out for Civitas, an independent thinktank, used local sentencing data released by the Ministry of Justice under freedom of information requests to track the effectiveness of penal policy and policing on recorded crime across the 43 forces in England and Wales between 1993 and 2008.
The researchers concluded that prison was particularly effective in reducing property crime when targeted at serious and repeat offenders. They concluded that an increase of just one month in the average sentence length for burglaries - from 15.4 to 16.4 months - would reduce burglaries in the following year by 4,800, out of an annual total of 962,700.
The full report
will be published is available at civitas.org.uk Monday.