“crimes in Britain have fallen from about 20m in 1995 to about 12m in 2006”
(from this article on prisons)
ETA: the figures are apparently from here, and the writer obviously cherry-picked to prove his point. But the actual figures are even more interesting – crime rising slowly over the 80s, quickly through the early 90s, peaking in ’96 and dropping since. And no, I’m not quite naive enough to blame crime on the tories 
[And apologies to those of you to whom this is all old hat; I feel humbled by my total non-wonkiness, in having not the faintest idea about that trend]