Bravo for the Labour party and a new cadre of trade union leaders who this week showed unequivocal support for overhauling our archaic voting system. Labour conference delegates overwhelmingly backed a motion calling on the party to embrace proportional representation. How could it be otherwise when a fanatical cult of free-marketeers has seized power and crashed the economy? Progressives almost always outvote the right, according to the Electoral Reform Society. But the right nearly always wins under the current first-past-the-post system because the centre and centre-left vote has been fatally split ever since the rising Labour party failed to kill off the remnant of the old Liberals. At the last local elections, in 85% of seats just one rightist – a single Tory – confronted an anti-Tory vote split between two or three Labour, Lib Dem and Green candidates. Readers of these pages know the well-rehearsed reasons why the Guardian backs electoral reform. The political scientist Sir John Curtice says the system is now more biased towards the Conservatives than at any time since the 1950s, when Labour on its own outpolled them but lost. At the next election, the Tories only need a five-point lead to win, while Labour needs to be 12 points ahead because the latter’s voters are clumped in the same seats, while Tory supporters are spread more widely. According to political academic Prof Robert Ford: “Citizens living in countries with more proportional electoral systems are more politically engaged and turn out more in elections”, delivering “healthier democracies with happier voters”. And it’s easy to see why: voters here are confined to holding their noses and choosing between one of two big, uncomfortable coalitions: far left and social democrats in Labour, or pro-EU traditional Conservatives and far-right Brexit free-marketeers in the Tories. There is no hope for new parties and no way for voters to express a particular opinion, causing a dangerous disillusion with politics that threatens democracy itself. Roy Jenkins’ compromise solution, commissioned by Tony Blair – combining constituency links with a proportional top-up – sits gathering dust on the shelf. So what’s preventing Keir Starmer and his team from embracing what his party so demonstrably wants and what the majority of the public, for the first time, supports? Two things: one understandable, the other disgraceful. Starmer himself and most of those around him are instinctive reformers, for all the above good reasons. But they take fright easily, only newly arrived at believing they could actually win the next election. Might the chameleon Tories reform and revive in the next two years? Might those eternal zombies spring from their political grave? To do that, the Tories need to make the next election about anything except the economy, pay, the cost of living, sky-high mortgages and derelict public services. They will, no doubt, scramble for any culture war issue they can drum up, preferably a return to Brexitry. They will grub up any phoney distraction – and a Labour manifesto pledge to reform the voting system might just fit the bill. The Mail has been testing its teeth on this already: “Tory election planners fear Labour will back bid to axe ‘first-past-the-post’ system next month – risking a ‘coalition of chaos’ that could lock Conservatives out of power for a generation.” This week they stirred up MP Maria Caulfield, whose Lewes seat will probably return to the Lib Dems, to warn: “For all his bluster, Keir Starmer is keeping the door open to a grubby backroom deal with the Liberal Democrats because he can’t rely on running on his own record. And we know the price of Lib Dem support will be to renege on the referendum result and Brexit.” Never mind that it’s nonsense: the Conservatives might manage to make the Brexit threat fly, pretending that it is the price the Liberal Democrats would demand. It is true that proportional representation would prevent the Tories in their current demented form ever again winning alone. Imagine how they might blow this up into an entirely mendacious “Labour gerrymandering threat to democracy”. Look no further than the scandalous lies the no side told during the alternative vote referendum in 2011, preposterously claiming its cost would take money from babies’ incubators, as they cut their teeth on how to lie in the Brexit referendum. Does Labour really want to commit to an electoral reform referendum consuming its first few months? The complex pro argument will be hard to make against the hailstorm of the Tory press defending their indefensible electoral advantage. Fear that backing proportional representation could lose Labour the election is a genuine enough reason for concern. The disgraceful reason why a minority in the party, comprising tribal dinosaurs, reject it, however, is that it means Labour, too, would never win alone again, losing seats to the Greens and any new socialist party that may emerge. Since Labour rarely wins anyway, that’s a very bad reason. What matters is that progressives can coalesce to keep out the kind of right that has brought us to this crisis. A progressive coalition of well-defined parties commanding influence in government according to their strength would secure a progressive future. Letting extreme Tories win mostly is a rotten price for preserving the old Labour party. If Labour needs Lib Dem support to get its budget and legislation through, Ed Davey has to show he is no Nick Clegg by refusing absolutely without proportional representation, with or without a referendum. Clegg threw everything away, allowing a weak alternative vote system instead of proportional representation on the ballot paper, and failing to force David Cameron to back it. This time the Lib Dems will be wiser if they hold swing votes. They have learned bitter lessons. But if Labour wins outright, never mind what they timidly said before the election, they must do it. Remember what happened in 2010 with George Osborne’s first austerity budget: he swept away almost everything good Labour did in its 13 years because, aided by the folly of Lib Dems infatuated with red boxes, he could impose extreme policies. A proportional representation-elected Commons wouldn’t be able to command a majority for such extremism. Why yet again toil to bring in decent policies, only for the political pendulum to swing back and knock them all away again? This is a risk worth taking. Polly Toynbee is a Guardian columnist