The Guardian view on the Peterborough byelection: a populist backlash? | Editorial

Mainstream parties need to offer narratives, and policies, that address the underlying economic grievances of voters

Peterborough is a smallish city in eastern England with a fast-growing population of European migrants attracted by its factories, warehouses and agricultural work. On the edge of the Fens, it sits on top of two faultlines in British politics: those of culture and class. When the city voted to leave the European Union in 2016, it seemed to be reacting against the ethos of the times - against immigration, against diversity, against pluralism. But less than 12 months later, in the general election, Jeremy Corbyn's leftwing Labour party won in Peterborough. Despite Ukip pulling out to avoid splitting the rightwing vote in 2017, Stewart Jackson, the pro-Brexit Conservative MP, lost his seat.

With recent history as a guide, it might seem that when elections in places like Peterborough are fought on the territory of identity, the battle favours the right; when the contest is about economics, then progressives find the going easier. If that is the case, then both the main parties, so badly bruised by last month's European polls, have much to fear this week in Peterborough - not least as the byelection only came about because the former Labour MP, Fiona Onasanya, was removed by a recall petition after being jailed for lying about a speeding offence. With Britain's future relationship with the EU still unresolved, Nigel Farage's rightwing populist Brexit party looks set to mop up.