Zack Polanski attends a gathering in Hackney. Photo by Julio Etchart/ Alamy If it really does come to pass this May and afterwards that the Green Party breaks Labour’s century-long hold on the British left, then 26 February 2026, when the Greens won their first parliamentary by-election in Gorton and Denton, will become a famous day. That morning I left my shared flat, went up the stairs to Hackney Central Overground station, and on the platform ran into a man in a green parka looking at his phone. I wished Zack Polanski luck as the train arrived. He went off to Manchester and a measure of victory that would have been unimaginable even a year ago – then he came back to Hackney and dreamed of far more. The north-east London borough is now a cradle of Green ambition. It has been a Labour stronghold since today’s boroughs were invented but is predicted to fall to the Greens in May.…