Left, right and centre – I see all strands of the Labour tribe pulling together in Makerfield. This is bigger than Burnham | Polly Toynbee

Everyone here knows this is a sliding doors moment. A win could be a new beginning for the party, a loss an unimaginable calamity

T hey flock to Makerfield from everywhere: canvassers and camera crews, MPs, peers and volunteers, from Swansea to Gateshead, 700 a day to help the Labour campaign. Every door has already been knocked four times, boasts the Burnham team.

How does it feel for voters to be the most important constituency in living memory ? Most are quite pleased, bar the usual “we only see them round here when they want our votes”. But with a chance to choose a prime minister , never was a vote so valuable.

Beyond Britain’s fate, the world sees in Makerfield a signpost on far-right populism: here, reporters have arrived from Italy, Germany, Sweden and five different Japanese TV news channels, among others. Expecting great rallies and flag-waving marches, they are crestfallen at nothing much to film beyond sparse signs on stakes in front gardens . This is a local, shoe-leather, person-to-person campaign by all parties. Andy Burnham himself leaves a personal video message for anyone who’s out, recorded on their front door security camera to show he really was there, with no grandstanding as he dashes around undecideds across the small towns here.

What a high-risk gamble to trigger an election here , rolling the dice in a constituency where every council ward voted Reform in May , making up part of Wigan, where 64% voted Brexit . Against that, Wigan voted 66% for Burnham as mayor , and he is the only popular senior politician in the country, the only one with a net favourable rating . To lose here would be an unimaginable calamity, everyone arriving at his HQ knows, clutching teas between canvass rounds. If not here, with this ultra-local man who offers them a rare chance to elect their own prime minister, then every one of Labour’s 402 MPs is in peril. Would the party survive?

The prospect of that cataclysmic wipeout has gathered a rarely united Labour campaign. Squeezed in a Makerfield taxi together was Tulip Siddiq – an ardent Keir Starmer loyalist, from his next-door constituency, who tells me that if Burnham wins he should make no leadership challenge – squashed up beside Miatta Fahnbulleh, the first minister to resign after the May elections because she and her constituents had “ lost faith and confidence in the prime minister ” for lack of clarity about “values” and “purpose”. How odd this campaign is, when Labour canvassers encountering “I hate Keir Starmer” (as voters often say, however unjustly) reply, in effect: “Vote for Andy to get rid of him.” The chief whip, Jonathan Reynolds, has been here , but who is he whipping to say what?

Look, there is John McDonnell, the Corbynite ex-shadow chancellor, pausing between canvasses to tell me what Burnham could do as PM: take control of water companies . No, Burnham need not be constrained by his pledge to stick to the manifesto, as there are wider interpretations available, he says. Torsten Bell, the former head of the radical Resolution Foundation, now Treasury minister, has a canvassing style that sees him bounding like a gazelle from door to door: a husband and wife give him a beaming thumbs up. He gets the best door-knock, when elderly Shirley says she has never voted before: “I’m not political.” But she will vote for Burnham. “Farage is like Hitler and Trump!” she says.

Someone could set up a profitable stall here, selling voxpops to any passing journo. When I worked in the BBC newsroom, it was easy: grab one of each, preferably in a picturesque market with a mouthy stall holder, and conclude “only time will tell”. I can take my pick here, but be none the wiser on the result.