Civil life in London is now balanced on a knife edge

I’m a member of a small and weird minority, the conservative urbanophiles. Obviously cities are nests of degeneracy and, even worse, the false faith of progressivism – my postcode voted 82 per cent Remain and the Tories finished fourth in 2015 – but nevertheless urbanisation is glorious, the best thing our species ever did. City life means socialising, culture and prosperity. 

But the English-speaking world forgot two important things about city life in the 20th century, lessons that have been painfully half re-learned: that cities should be beautiful and cities need to be civilised. The story of American urban decline in the late 20th century is especially tragic, hollowed out by architectural vandalism, community-destroying motorways, and most of all the breakdown of law and order. In contrast suburbanisation represented a retreat from public life. London is never going to reach US levels of violence and urban decay, partly because of our gun laws and the lack of available places for a middle class to escape to, but nevertheless the fourth fatal knife murder in