Calm down dear, it’s only a poll, and after 7 May, surely no one is much inclined to trust them. Except when, like this morning’s YouGov survey in the Times, they play into the kind of rightwing narrative that is determined to frame Labour as the Syriza of the north, with Jeremy Corbyn as an older version of Alexis Tsipras.

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Peter Kellner, who runs YouGov, will have been extremely cautious about his methodology, and if the poll had been presented in the light of his health warnings – it was, he said, “a grainy snapshot of the Grand National about halfway through the race” – it might not have dominated the news this morning the way that it has.

No one can claim to know this new self-selected electorate, created as a plunge in the dark by Ed Miliband to try to escape from the shadow cast by his own dependence on union votes. There is just under a month before the cut-off date of 12 August in which another few hundred thousand people can pay their £3 and buy themselves a vote. There is also still time to step off the cycle of recovery that the experience of the Tories after 1997 seemed to establish for a party thrashed in the polls after a prolonged spell in power.

Jeremy Corbyn as leader would fit tidily into the pattern the Conservative party established in its wilderness years. First was William Hague, someone who looks like a compromise between the soul of the party and a saleable product. Then came Iain Duncan Smith, a man with a direct line to the soul of the party but the electoral appeal of a family pet with an uncertain temper. Then finally, after the nightmare, the awakening and selection of a leader who actually looked and sounded plausible.

Labour cannot afford to indulge in that kind of protracted crisis. Britain cannot afford Labour to indulge in a protracted crisis.

I remember when Michael Foot led the party and it couldn’t organise a coach trip without getting stuck under a bridge

There is room for a party of the emotional spasm in British politics but that is a party of protest, not a party of government. Labour is a party of government. That means it has to shape and articulate the beliefs and aspirations of a majority of its citizens, not just an apocalyptic tendency. That was the point Tony Blair was making this morning.

When I first became a journalist, the best event of the year was always the Tribune rally at Labour’s annual conference. Held in a huge, smoke-filled, packed-out hall, speaker after speaker – these were the days of early Neil Kinnock and David Blunkett – made funny, impassioned, venomous, brilliant speeches that sent us out into the night full of righteous anger.

I remember when Michael Foot led the party and it couldn’t organise a coach trip without getting stuck under a bridge. I wrote about splits and walk-outs and rows and hair-pulling in the ladies at the Grand in Brighton. I remember Labour facing oblivion – very nearly beaten into third place by the SDP in 1983 – and the long, hard struggle to re-establish the party as a serious force in politics.

Please, new associate members who will shape the party for the next five years, maybe forever: do a little research. Think what kind of country you want for you and your children and, even more importantly, think how you might get there. Now think, is Jeremy Corbyn in the middle of that picture? I don’t think so.