“Perhaps we will wake up on Saturday afternoon and find it has all been a bad dream.”

Ahead of the election of their new leader, in the Guardian Andrew Rawnsley samples the mood, of despair, among the moderates of the parliamentary Labour Party.

Labour MPs, as a collective, are still getting their stunned heads round what is happening to their party. Because the hard left had been fought – and apparently crushed – so long ago, it simply did not occur to them that it might revive, least of all in the person of a 66-year-old colleague who has been an eternal backbencher since he first arrived in parliament as a disciple of Tony Benn and an enthusiast for the calamitous 1983 manifesto. Because it was so self-evident to his colleagues that the Corbyn candidacy was a joke they did not wake up to its potency until too late. Yet there had been warning signs of the potential for this to happen in the surge of populist left movements elsewhere in Europe, thriving on discontent with austerity and rage against elites. Closer to home, the rise at Labour’s expense of the Scottish Nationalists ought also to have sounded alarms. “Scotland should have told us about the power of emotion and identity in politics,” admits one member of the shadow cabinet.

Allied with those failures of inspiration and imagination has been a disastrous lack of mobilisation. One candid senior Labour MP on the team of one of Mr Corbyn’s leadership rivals says: “We completely fucked up organisationally.” The biggest mistake made by all three of the mainstream contestants was not to grasp the implications of the change to Labour’s system of leadership election. When that went through, in early 2014, something strange happened. Len McCluskey and the other chiefs of the big unions, who had initially been highly hostile to scrapping the electoral college, suddenly dropped their opposition and came along very quietly. I think it is now becoming clearer why. They had started to work out what the changes could mean and how they might be exploited with a systematic drive to sign up supporters for their niche of left politics. About half of the union members with votes in the contest have been signed up by Unite, whose executive were early endorsers of Mr Corbyn.

At the time of the rule change, there was not much comment about the potential effects of allowing registered “supporters” to buy a vote in exchange for the price of a pint. A couple of people on Ed Miliband’s senior staff did think through some of the implications. They argued with him that they should start to actively recruit £3 supporters to try to ensure that the party drew in people who were reasonably representative of the sort of mainstream voters Labour needed to win general elections. That idea was resisted by other members of the Miliband team. “We’ll only get hippies,” sneered one naysayer. So that initiative came to nothing and the composition of the selectorate continued to slide left, a process which has dramatically accelerated during the contest.

Labour modernisers, who had argued for years for one-member-one-vote, gave little thought to the change. There was no effort to recruit centre-left voters as Labour supporters. The machine behind Mr Corbyn did think about how the new system might change the dynamics of a contest and all credit to them for seeing a path to victory by allying old-style trade union organisation with the newer power of social media.

The MP for Islington North was alone among the candidates in putting on his campaign website a link to the £3 sign-up. The teams of all three of his rivals made a terrible mistake in not spotting how this would radically influence the race. In mitigation, one member of the shadow cabinet pleads that they were all too distracted by the shock of the general election defeat.

“While we had our heads under the bonnet of the car trying to work out why we lost the election, these people jumped into the car and drove it off.”

Which leaves stunned Labour moderates stranded on the kerbside, aghast at where the car is now heading, unsure when or how they will get it back and fearful that it might be a write-off by the time they do.

Read the whole thing.