In 1850 Thomas Carter, the Anglican chaplain of the Liverpool Borough Gaol, admitted that ‘our town has been acknowledged to be one of the most unhealthy towns in the kingdom. It is certainly notorious for being (so far as the criminal statistics show it) the most immoral.’ yet in the same year the Liverpool Mercury warned, ‘There is nothing more dangerous, in our estimate of the causes of social evil, than an implicit reliance on statistical information.’

Crime statistics have always been a problematic guide to both the amount and the type of criminal activity. For a start, a great deal of crime goes unreported and hence unrecorded, the so-called ‘dark figure’. In a lecture on ‘Liverpool Slum Life’, delivered in 1894, local JP and temperance campaigner Dr Whitford revealed the uselessness of crime statistics. On the one hand, the head Constable's report could boast that there had been no significant increase in crime during the year. At the same time the Liverpool Mercury was informing its readers ‘that the Liverpool slum dwellers are at present more degraded, more drunken, and more lawless than at any time during the past 15 years’. Whitfeld helped explain the discrepancy by pointing out several cases of violent robbery that were never reported to the police. In the slums, intimidation and terror were so common that most people were afraid to complain. He concluded that ‘most of the crime in the Liverpool slums never appears in any police return’.