The crime rate in early 20th century Britain was low, lower than for the early 19th century. Even the terrible poverty and unemployment of the 1930s appeared to bring only a small increase in crime. Then from about 1960, crime figures seemed to rocket upwards. What was going on?
A simple comparison of some crime figures for 1900 and 2000 shows the impact of this:

The "crime wave", as it was called, seemed all the harder to understand as it went along with greater national prosperity, peace and security. It became a political issue, with parties vying with each other for the "answers" and each accusing the other of being responsible. This meant that the crime figures themselves became the focus of political argument.
A glance at the table above will show that the increase in the three types of crime listed is not the same. But as 20th century crime statistics became more detailed, they only led to further arguments over interpretation. What types of crime were increasing? Was the increase slowing down? What did it all mean anyway?
Then there was always the problem of the "dark figure". This is the difference between the numbers of crimes committed and the number reported. The "dark figure" exists, but no one knows how big it is, or if it is changing. For example, there was a 100% increase in the number of reported burglaries in the 1970s, yet only an 18% increase in the number of people who said they had been burgled. It would seem that burglary was increasing, but not as fast as the reported crime figures.
It seems that the "dark figure" is shrinking as more crimes get reported: the police encourage the reporting of crime; insurance claims make it necessary; more people have telephones. Police reporting and acting on crime reports is also now far more thorough.
Newspaper crime reporting may also exaggerate the actual amount of crime. The newspapers like to report crime, and to sensationalise it. One effect of this is fear: people are more afraid of crime, even when, in fact, they are at no more risk than in the past.