Jeremy Corbyn has defied the pundits and the pollsters to restore the Labour party as a serious electoral force and deliver a devastating blow to Theresa May’s political authority. But how?

This remarkable election saw a surge in both Conservative and Labour votes as the first-past-the-post system amplified the return of the two-party system after an absence of nearly 20 years.

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More than anything else it was a night in which Britain’s younger generation flexed their political muscles to real effect for the first time.

Despite their calamitous campaign, the Conservatives increased their share of the vote to 42% – up five points since 2015 – which in any other election in the past three decades would have been enough to build a commanding majority.

But Labour outperformed even that achievement as a unique alliance of enthused younger voters and previous non-voters combined with older austerity-hit, anti-establishment Ukippers to deliver a 10-point rise in Labour’s vote compared with two years ago, to 40%. This is just below the 41% secured by Tony Blair in his 2001 landslide victory.

Turnout

The “youthquake” was a key component of Corbyn’s 10-point advance in Labour’s share of the vote – exceeding even Blair’s nine-point gain in his first 1997 landslide. No official data exists for the scale of the youth vote but an NME-led exit poll suggests turnout among under-35s rose by 12 points compared with 2015, to 56%. The survey said nearly two-thirds of younger voters backed Labour, with Brexit being their main concern.



Overall turnout was up 2% at 69%, the highest since 1997, with 85% of seats seeing an increase in voters. The top five seats with the highest turnouts of 78-79% were Winchester, Twickenham, St Albans, Wirral West and Wirral South. The first three featured fierce Lib Dem/Tory battles, including Vince Cable’s successful fight in Twickenham.

Ten seats that saw the largest 10%-plus increases in turnout included Newcastle upon Tyne East, Ilford South, Foyle, Rossendale and Darwen, Lewisham East and Staffordshire South. It is likely the youth vote had a decisive influence in seats such as Manchester Central, Canterbury and Cambridge, which are also in the top 22 seats for increased turnout.

London experienced the biggest concentration of seats with above average turnout, 39 being above the national 69% benchmark. The largest turnout falls came in Scotland, where 20 SNP-held seats recorded drops of up to 8%, marking a turn in the nationalist tide. Only two seats in Scotland saw increased turnout – Orkney and Glasgow.

What happened to the Ukip vote?

Analysis of the local election results led many to conclude that the shift of Ukip’s 4 million former voters had almost all gone directly back to the Conservatives. They appeared to be fuelling the massive 15-point-plus Tory leads when the snap election was called and confirming Boris Johnson’s claim they were “a lost Tory tribe”.

But the data shows that picture to be a lot more complicated; the Ukip vote has fragmented, with more than a third going to parties other than the Conservatives. In at least one seat – Canterbury – where Labour won for the first time – Ukip’s failure to stand in a constituency where it secured 7,289 votes in 2015 seemed to fuel Labour’s 12,000 vote increase. In Wrexham, another seat where Ukip stood down, it appears Labour and the Tories equally benefited from Ukip’s former voters, keeping the seat Labour despite its high leave profile.

This fragmentation of the Ukip vote also enabled Labour to hold on to Nottinghamshire marginals, such as Vernon Coaker’s Gedling. The much-touted Tory surge across the Midlands, the north-west and the north-east failed to materialise, partly as a result of this effect. Nigel Farage claimed the Conservatives had made a major miscalculation in assuming Ukippers were just disaffected Tory voters.

Marginals

The new battleground seats include some unfamiliar names, such as Kensington in London, as key marginals. In Hastings and Rye the home secretary, Amber Rudd, now sits on a majority of just 346 and may have to spend more time in her constituency if she does not move to safer territory.

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The Tories are now defending 40 seats which are vulnerable to a swing of just 2.5%, while there are only 29 Labour MPs sitting on such a slim majority. This advantage to Labour, however, may be eroded when the new constituency boundary changes come into effect next year which were expected to benefit the Conservatives..

The swing

There were fears during the campaign that the Corbyn surge, fuelled by big Labour leads among voters under 35, would simply stack up bigger majorities in the party’s safe seats. But Labour made gains across the country in unexpected places, such as Canterbury, Plymouth and Ipswich, while the Tories saw their more modest but still substantial increase in support concentrated largely in the seats they already held.

The national swing from Conservatives to Labour was 1.8% but there was a sharp Brexit variation between remain and leave seats.



The results show an 8% swing from Conservatives to Labour in those seats that voted remain in last year’s referendum. In seats that voted leave there was a 1% swing from Labour to the Conservatives. It appears Corbyn’s fudged Brexit stance proved highly effective in minimising defections among leave voters while still proving positive enough for unhappy remain voters, especially in London.

May v Corbyn

It was also very much a personal triumph for Corbyn. The Conservatives, fuelled by a stratospheric +28-point approval rating for May, far outstripping her party’s standing with voters, chose to base their campaign around her. The word “Conservative” was reduced to a footnote.

Corbyn’s ratings began at -23 points and he faced a campaign of vilification in the Tory papers not seen since their 1980s assault on Michael Foot. Corbyn minimised the damage through his unplugged style of mass rallies, growing in strength through the campaign and eschewing May’s itinerary of highly targeted marginal visits.



He ended the campaign with a remarkable YouGov personal rating of +39. May, whose wooden leadership and shortcomings became painfully plain to the public in the full glare of the campaign, finished on a rating of +6. She was no longer the electoral asset her party had invested in so heavily.

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Two-party politics

But the election was not a uniform national story. Labour gained most in London and produced good results in Wales. Meanwhile, the most effective part of the Tory surge came in Scotland, where they won more seats from the SNP than Labour.

It was, however, overwhelmingly a realignment among the parties’ voters that produced this hung parliament. Labour gained strongly among younger, more affluent urban voters while the Conservatives reached working-class voters who had never supported them before.

The big casualties were the minor parties, with Ukip being the biggest. Its vote fell from 13% in 2015 to 2% and the party faces implosion after the resignation of its leader, Paul Nuttall. It was a happier story for the Liberal Democrats, despite losing Nick Clegg. The party’s national vote share was little changed at 7% but its strategy of fighting the campaign as a series of individual byelections paid off, increasing the number of seats from eight to 12 – its first advance since 2005.