The Green surge shows British politics has reached a turning point - and it has surprisingly little to do with Zack Polanski | Aditya Chakrabortty

At a party event in a school hall in Lewisham, people told me how disillusionment with Labour has led to this moment “How many?” On the end of the phone is a nice press officer for the Greens, head full from a long day in Gorton, Manchester, showing off their would-be MP. And now, as Friday’s sky turns indigo, I’m calling about reports from Lewisham, south London, that tomorrow they’re expecting a flood of 500 Green activists. This comes as a surprise to the party’s own news machine. Aditya Chakrabortty is a Guardian columnist