The most recent figures from the Metropolitan Police show that in the 12 months to the end of August this year it went up by 6%. During that period the police recorded 10,058 offences. But 3 years ago the figures were much worse. In the 12 months to the end of November 2011 there were 14,570 recorded offences.
It then fell by 35% to its lowest point in recent times in November last year before beginning to rise again slowly.
The figures for knife crime with injury where someone was actually cut or stabbed rather than threatened show a similar pattern, falling from a peak of 4,200 in the 12 months to the end of March 2010 to a lowest point in April 2014, since when it has risen slightly.
The chief of the Metropolitan Police, Sir Bernard Hogan Howe, has linked levels of knife crime with a reduction in use of powers where officers can stop and search people if they have reasonable grounds to believe that they are carrying drugs, a weapon or stolen property. In a public criticism the Home Secretary Theresa May described that as a knee-jerk reaction.
The figures for the stop and search have fallen from a peak of 527,000 in the 12 months ending March 2011 to just 149,000 in the 12 months to August 2015.
This is a steady drop from peak to trough of 71% and does not have an obvious correlation with knife crime which was falling for much of the period as stop and search was falling.