Sentencing and Knife Crime

This article from the Economist makes fascinating reading on the fall in violent crime and the apparent disconnect with policy, which seems set on ever tougher measures such as mandatory sentences despite falling numbers of both fatal stabbings and knife wounds. Of course, a fall from 272 to 194 fatal stabbings per year over a six year period does not alter the tragic consequences of knife crime in each case.Both Conservatives and Labour appear to support the proposal that adults convicted of a second knife offence should automatically get at least six months in prison.In the light of concerns over the perverse consequences that some argue flow from mandatory sentencing, is the law being used as an election megaphone, as the Economist suggests? Or is this the tough approach the crime in question requires?