LONDON (Reuters) - Prime Minister Theresa May faced calls to quit on Friday after her election gamble to win a stronger mandate backfired and she lost her parliamentary majority, throwing British politics into turmoil and potentially disrupting Brexit negotiations.
Below is a list of the 100 most marginal seats from 2015, ranked from smallest vote margin to largest and showing the swing that had been needed for seats to change hands.
Labour hung on to many of its smallest margin seats, and made gains from the Conservatives.
Below are some key developments so far:
The first Labour gain of the night. Some polls had showed the Conservatives doing well in Wales, where most people voted to leave the European Union. But Labour overturned a thin 237 vote margin, increasing its vote by around 12 percentage points
Liberal Democrat Nick Clegg was deputy Prime Minister little over 2 years ago, but he lost out to Labour after Conservatives, who had backed him tactically in 2015 following the two party's time in coalition government, returned to voting for the Conservatives.
The Conservative share of the vote rose 10 percentage points, while Labour increased their share by just 2 points. Thar was enough to produce a near 6 point fall for the Lib Dems, and hand Labour the seat.
This marginal seat had been held by the Conservative minister responsible for financial services, Simon Kirby, with a majority of just 690. It voted strongly in favour of remaining in the EU and Labour surged to take the seat.
It has been a bellwether at national elections since 1979 and the Green Party, who won more than 3,000 votes here in 2015, did not stand.
Considered a national bellwether seat, holding Nuneaton gave May's Conservatives a early boost, which proved to be illusory. They increased their majority here in 2015, despite it being a Labour target, and it provided one of the first indications the Conservatives were on course for victory. However, Labour also increased their share of the vote in the seat, as support for the anti-European Union party UKIP collapsed.
This was a key Conservative target seat, which voted in favour of leaving the EU. But Labour held the seat, with both parties increasing their share of the vote by about 8 percentage points.
This had been a Conservative-held marginal seat, with a majority of just 378 voters. It has been a bellwether seat so the fact the Conservatives lost it, despite facing no UKIP candidate, supports the view that they could lose their majority.
Canterbury, which had been Conservative since 1918, saw the Labour party's vote share rise by over 20 percentage points, in a stunning victory. Labour won the seat by fewer than 200 votes
London, which voted heavily to remain in the European Union last year, saw big swings to Labour in many places.
British junior finance minister Jane Ellison was defending a 15 percentage point lead in Battersea in London, but the strongly pro-Remain seat voted Labour. The opposition party increased its share of the vote by 9.1 percentage points, while Conservative share of the vote dropped by nearly 11 points.
Labour's Rupa Huq had just a 274 seat majority in 2015, but gained a massive 16.5 percentage point increase to record nearly 60 percent of the vote it the strongly pro-remain seat.
Conservative MP Gavin Barwell had one of the slimmest majorities in the country, and lost his seat as Labour benefitted from support in remain-voting patches of London
Labour weren't the only party to do well in London. the Lib Dems retook Twickenham, a seat they had lost in 2015. Vince Cable, who served in cabinet in the coalition government between 2010 and 2015, regained his seat.
The Scottish National Party, which dominated in Scotland in 2015, suffered some notable losses
The Conservatives won several key seats in Scotland from Nicola Sturgeon's Scottish National Party, delivering a blow to the party that had a near clean sweep in Scotland two years ago.
SNP veteran and former leader Alex Salmond lost his Gordon seat as the Conservative Party surged in Scotland. Colin Clark defeated Salmond, who was also Scotland's first minister between 2007 and 2014, by 2,607 votes. Salmond said people had not seen the last of him.
The Conservatives also took Moray from the SNP, unseating the party's leader in Westminster Angus Robertson. While Moray voted to remain in the European Union, it did so by the tightest margin in Scotland, and was strongly against independence in 2014's Scottish referendum.
In Angus, the Conservatives overturned an 11,230 SNP majority to win by 2,644 votes,
Labour used to be dominant in Scotland, and showed a few signs of a comeback, picking up several seats that had rejected independence in 2014.
Popular ex-MP Jo Swinson regained her seat, just two years after she lost it to the SNP
Reporting by Kylie MacLellan, Alistair Smout and Jon Coffey; editing by Guy Faulconbridge and William James