Photo by Leon Neal/Getty Images Standing on the steps of Hackney Town Hall earlier today (8 May), Zack Polanski declared the era of two-party politics “dead and buried”. The Green Party leader was speaking shortly after Zoe Garbett was elected as Hackney’s first non-Labour mayor. At the time of writing, Polanski’s party now has more than 1,000 councillors in England, has squeezed Labour’s vote in Manchester and Exeter, and looks set to make a major breakthrough in the Senedd in Wales. After a difficult campaign, in which his party was wracked with accusations of anti-Semitism among its candidates, Polanski has begun his victory lap. But is it premature? Hackney was one of the Green Party’s primary targets. Labour had spent almost a quarter of a century in power in the east London borough. But Garbett won by an even bigger majority than the Greens’ performance in the Gorton Denton by-election in February, taking almost half of the vote (47.2 per cent).…