Here's an exchange that took place around 53 minutes into Wednesday's mayor's question time : James Cleverly AM (Con) : "What is actually happening with serious youth violence in London? Boris Johnson : "Serious youth violence is, I'm pleased to say, is coming down." And here's what Metropolitan Police commissioner Bernard Hogan-Howe writes in paragraph 13 of his report to next week's meeting of the full Metropolitan Police Authority, comparing April to September 2011 with the same stretch of time last year: The overall number of victims of Serious Youth Violence increased by 9.5% (328 more offences from 3,435 to 3,763) over the 6 month period. Boris's false claims and figure-fiddling over crime are fast attaining elephantine scale. In February, he associated himself with falls in public transport-related offences that happened six months before he'd made any changes to the relevant policing arrangements and four months before he'd even become mayor. His efforts to divert attention from having been caught out repeatedly misrepresenting the achievements of his youth offender re-settlement project, included calling the distinguished chair of the independent UK Statistics Authority " a Labour stooge ." Adam Bienkov has revealed that his campaign website too is a treasure trove of crime stat spin and plain inaccuracy. Let's try to get an honest handle on all this. As I wrote last week at Comment is Free , there is a large, good news story about crime in London and a smaller, very bad one. The good news story is that overall reported crime has been in general decline in the capital for years, a trend that far pre-dates the arrival of Boris at City Hall. The bad news story is that serious violent crimes against children and young people are following a different trend from that for crime overall. While all youth violence - offences against under 20s - came down slightly during the first three years of Boris's term, the offences categoried by the Met as "serious" crept up - and as Bernard Hogan-Howe's report reveals, that has continued. Furthermore, there was a very large jump in the number of 13-24 year-olds injured with knives in the second and third years of Boris's term compared with the first, despite the Met's increased use of the stop-and-search tactic and the introduction of knife-detecting arches at transport hubs. The commissioner's report also confirms that "London has experienced an increase in knife crime offences over the last three years which has continued in 2011," adding that "offences are now almost one fifth higher than 2009 levels." Boris came to power promising to vigorously tackle serious youth violence and knife crime. As he seeks re-election he is claiming to have achieved a great deal. As his police commissioner has now helpfully testified, these claims seem not to be based in reality. Boris Johnson London politics London Crime Police Bernard Hogan-Howe Dave Hill guardian.co.uk © 2011 Guardian News and Media Limited or its affiliated companies. All rights reserved. | Use of this content is subject to our Terms & Conditions | More Feeds