When it came, the exit poll projecting a hung parliament was as surprising to Labour’s campaign team as to everyone else. One of them, who was with others bunched around a TV at the party headquarters in Victoria Street, London, said: “We were absolutely buzzing.”

There were words of caution that exit polls had proved unreliable in the past. One warned: “Let’s throttle this back.” But it was too late.

Andrew Murray, one of Jeremy Corbyn’s advisers, who helped write his manifesto speech, said: “There was a tremendous moment of elation when the exit poll was announced because it became apparent that the campaign had achieved the most stunning turnaround in public opinion in seven weeks.”

On Thursday morning, the team had prepared plans for about half a dozen scenarios. The best-case scenario, regarded as highly unlikely, was forming a government. The second best, viewed as almost as unlikely, was a hung parliament. The worst case, based on one of the worst of the polls, was the Conservatives on 380 seats, with Labour dropping to 190.

The scenario the team expected to be dealing with was one in the middle, which put Labour on about 35-36% of the vote.

Murray, seconded to the campaign from Britain’s biggest union Unite and demonised in the tabloid press as a Stalinist because he had been a member of the Communist party, spoke of the joy that engulfed the 8th-floor Southside office. “We had gone from mid 20s in the polls at the start of the campaign to denying the Tories a majority. It was a moment of shared achievement.”

At the start of the campaign seven weeks earlier, the mood of the advisers, friends, union general secretaries and others around Corbyn was doom-laden, speculating on whether he would have to resign if the election went badly and, if he did not, whether the Labour right would mount another challenge to him.

But now Corbyn, emerging from the campaign with his reputation enhanced, seems unassailable, his standing among the membership probably even higher than it was in the two leadership contests, and the Labour right dropping plans for the time being to challenge him. “It would be a fool’s errand,” one of Corbyn’s team warned.

Around the TV in Labour HQ on Thursday night were, in addition to Murray, Andrew Fisher, Corbyn’s head of policy who hastily compiled the manifesto that was to prove so popular, and Steve Howell, deputy director of strategy and communications. The other two who make up the core team were with Corbyn at his Islington home; Karie Murphy, his office manager, and Seumas Milne, the director of strategy and communications, who, along with shadow chancellor John McDonnell, is closest to the Labour leader.

Corbyn, watching the exit poll announcement on television, was less effusive than those back at HQ. Displaying the same sense of calm as he did throughout the campaign, he smiled.

The campaign team began each day with a conference call at 7am. Some were already in the office, others joining from home. As well as the core of five, others on the call included Corbyn’s political secretary Katy Clark and Niall Sookoo, who looked after the grid of planned campaign events. Almost all of them worked in the office through to eight or nine in the evening and, from their homes, through to midnight and beyond.

At the start of the campaign, they identified two seemingly unscalable problems, in addition to poor poll showings. One was the loss of the bloc of Labour MPs from Scotland, down from 41 in 2010 to one in 2015, and no sign that having a leftwinger as leader was winning Scottish voters back. One of the major regrets now among the campaign team is that, having unexpectedly secured seven MPs, they did not put more resources into Scotland.

The other faulty assumption at the start of the campaign was that most of the former Labour voters who moved to Ukip would move on to the Conservatives. That so many of them came back to Labour is seen as a vindication of Corbyn’s line on Europe: a promise of a soft Brexit to appeal to the remainers in places such as London, and a promise to respect the outcome of the referendum to Brexiters in the north of England and elsewhere.

Early on, a decision was made not to waste effort on trying to win over a largely hostile print media and focus instead on broadcasters. Time with Corbyn for print journalists was scaled back.

May’s popularity was viewed at the start of the campaign as a problem and Corbyn’s team – but not Corbyn, who does not engage in personal abuse – discussed how to to tackle this. In the end, no move was necessary after May imploded in the aftermath of the Conservative manifesto launch, her repeated failure to debate and awkward, and rare, press conferences.

The low point of the seven weeks – apart from the Manchester and London terrorist attacks – was seen as the aftermath of the council elections on 4 May in which Labour lost hundreds of seats, just as the campaign was gearing up.

Labour enjoyed a long surge – though it twice stalled – but early this week it finally seemed to falter and there was a sense of deflation among those around Corbyn in the final phases. The campaign team made a decision that was to prove pivotal: to put more resources into and push even harder in initiatives aimed at getting out the youth vote in the final few days.

One of the recognised campaign weaknesses was a lack of shadow cabinet members experienced enough to take on high-profile media roles.

Corbyn could bring in some of the better-known MPs who refused to serve, though he is reported to be inclined for the most part to stick with those who have been loyal to him. One casualty could be the shadow defence secretary, Nia Griffith, who is regarded as having undermined him and shadow foreign secretary Emily Thornberry over Trident.

Corbyn is in a stronger position to see through reforms to consolidate the hold of the left on the party, such as changing the leadership rules to make it easier for leftwingers to stand.

His team believe the Conservative-DUP coalition is unsustainable and that there will be an early election, a prospect they welcome, with time to prepare and to consolidate and build on the base of support they have achieved over the last seven weeks.

Those in the party sceptical about Corbyn say he is still out of touch with the public mood. But those around him were celebrating on Friday. “The centre ground has shifted. This makes socialism a viable option again after a 30-year hiatus,” one said.



A senior Labour adviser said: “The argument that Corbyn could only appeal to party activists has been shown to be wrong by this campaign. The rallies and meetings across the country go far beyond this.”