. . . when will it happen? A highly interesting analysis here looking at the current (and previous) government(s).
There seems one possible explanation: public policy is too often made in reaction mode chasing newspaper headlines, where there always seems further bad news to report on criminal activity (even where crime is at historically low levels).
How can any government expect criminals to be deterred by hastily determined (and often incoherent) policies drawn in reaction to media organization attempts to attract customers and advertising revenue?