Crime in London, as in other places, is very hard to measure. Police figures generally understate crime substantially and can be extremely misleading. Accordingly, recorded crime statistics need to be treated with great caution and have sometimes been shown to show opposite trends to victim surveys or to violence as measured by hospital intake. However, police figures are usually the only available way to gauge local crime.
Greater London is served by three police forces; the Metropolitan Police which is responsible for policing the vast majority of the capital and is geographically divided into 32 Borough Operational Command Units, the City of London Police which is responsible for The Square Mile of the City of London, and the British Transport Police which polices the rail network and London Underground.
A fourth police force in London, the Ministry of Defence Police, do not generally become involved with policing the general public. Within the Home Office crime statistic publications Greater London is referred to as the London Region.
Crime rates vary widely by area: several have problems with crime, while many others are very safe.
Until the late 1990s crime figures for varying crime types were not released to the general public at individual police force level. The annual publication 'Crime in England & Wales' produced by the Home Office began to break the figures down to a smaller area in 1996. Crime figures in England & Wales during the late 1990s and early 2000s were often misinterpreted in the media and scrutinised because of frequent changes in the way crimes were counted and recorded that lead to rises in the crime category 'Violence Against the Person'.
Commenting on figures from 1 April 1998 onwards, the then-Home Secretary Jack Straw said "changes in the way crime statistics are compiled are in line with recommendations by senior police officers. They are intended to give a more accurate picture of the level of offences". The largest increases were recorded in the "Violence Against the Person" category owing to the inclusion of common assault figures to accompany other offence types within this category that include assault occasioning actual bodily harm, grievous bodily harm, harassment, murder, possession of offensive weapons and a selection of other low volume violent crimes grouped together by the Metropolitan Police as 'other violence'.