“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.

“Are you sure?”

My figures turn out to be wrong. It’s nearer 600.

On a dreary Saturday morning, they stream in from all over London, hare along Kent’s A-roads, pour off Suffolk and Surrey trains, to converge on this primary school. It’s the largest venue the volunteers could hire and the corridors, the loos, even the little library with its impressive range of Julia Donaldsons, are all heaving with grownups.

We cram into the assembly hall, where the crowd is declared as the biggest turnout in Green history. The sole exception, I find later, is polling day of the last general election; yet today’s draw is not some short, sharp fight for Westminster, but a campaign for the council, where ballots are months away. In normal times, this stuff is about as pedestrian as politics gets, drawing a handful or two of diehards to trudge door to door, begging old customers to put their X in the usual spot.

Yet the size of today’s crowd tells you these aren’t normal times. This winter is a hinge moment in British politics, the point at which the default choice of leftwing voters is no longer Labour. In Wales, it will be Plaid Cymru; in Scotland, the SNP. And in this corner of inner London, as in many English cities, it will be the Greens.

For this position, the party owes much to its opponents, among them Jeremy Corbyn, Zarah Sultana and their genius advisers for so........

© The Guardian