It sounds like a band. Once more the State of London Address took place at the O2 Indigo theatre. Each time the theme is different. This year knife crime. What is the Mayor doing to prevent it? Quite a lot it seems. The public health approach is the best way to tackle this, starting early and supporting children to divert into socially supportive activities. Then housing. A major problem. Not that there is a shortage of homes - they are lying empty, bought as foreign investments or beyond the reach of the majority of incomes.