London (CNN) In what is threatening to be an election nightmare for the opposition Labour Party, a 20-year-old Scottish student has become Britain's youngest lawmaker since 1667 -- ousting one of Labour's top figures in the process.

Politics student Mhairi Black, representing the pro-independence Scottish National Party (SNP), took Paisley and Renfrewshire South, a constituency outside Glasgow, from Douglas Alexander, Labour's election chief and a former Cabinet minister.

"It has clearly been a very difficult and disappointing night for the Labour party," Ed Miliband told supporters as he retained his own seat. He cited a "surge of nationalism in Scotland" as having affected the Labour party's results.

Scotland, traditionally kind to Labour, turned it back on the Opposition in favor of the SNP.

Labour's Scottish leader, Jim Murphy, lost his parliamentary seat to Kirsten Oswald, another largely unknown challenger, while former British Prime Minister Gordon Brown's old seat also went to the nationalists.

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The SNP's Alex Salmond, who led Scotland as First Minister and pushed for the unsuccessful independence referendum last year, won a seat at Westminster.

But the night belonged to an ecstatic Black.

"I pledge to use this voice not just to improve Scotland, but to pursue progressive politics for the benefit of people across the UK," she told supporters during her acceptance speech.

Mhairi Black took what should have been one of Labour's safest constituencies.

The Liberal Democrats, junior partners in the previous coalition government with the Conservatives, also lost some key figures -- chief among them Danny Alexander, Chief Secretary to the Treasury; Vince Cable, the Business Secretary; and Simon Hughes, a former London mayoral candidate. Current leader Nick Clegg, who was Deputy Prime Minister, held his seat.

Conservative gains

By contrast, the Conservatives were touted to make big gains with no real surprises so far -- Prime Minister David Cameron held his seat, while London Mayor, Boris Johnson, won a place in parliament.

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Two British broadcasters have adjusted their forecasts, with CNN affiliate ITN suggesting Cameron's Conservatives will win an absolute majority of 327. The BBC is forecasting 325 for the Conservatives. That would also be enough to govern alone -- parties need at least 323 seats to achieve an absolute majority.

Even though the final tally isn't in, one thing is clear: This is an election you should be paying attention to, even if you're not one of the millions of Brits who cast a ballot.

The vote could reshape the country's global role for years. Britain's relationships with the European Union, NATO and the United States are hanging in the balance. And a boost for the Scottish National Party could fuel a fresh push for Scottish independence.

'Most important election in a generation'

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As he campaigned this week, Cameron touted what he said was the country's economic recovery under his Conservative leadership. "I've now laid my brick," he said, claiming that the big payoff is yet to come for Britain as the country builds on the work he's done.

He said that if he was re-elected, he would hold a referendum on Britain's membership in the European Union.

On the other side, the Labour Party's Ed Miliband -- who prides himself in standing up to U.S. influence -- had promised higher taxes on the wealthy and the protection of Britain's public health system.

Photos: UK party leaders Photos: UK party leaders David Cameron became the Prime Minister of the United Kingdom in May 2010, leading a Conservative and Liberal Democrat coalition government. He is the current leader of the Conservative Party. Hide Caption 1 of 7 Photos: UK party leaders Ed Miliband is the leader of the Labour Party and the opposition leader in Parliament. Hide Caption 2 of 7 Photos: UK party leaders Nick Clegg is the current British deputy prime minister and the leader of the Liberal Democrats. Hide Caption 3 of 7 Photos: UK party leaders Nigel Farage is the leader of the Independence Party, a populist political party. Hide Caption 4 of 7 Photos: UK party leaders Natalie Bennett is the leader of the Green Party of England and Wales. Hide Caption 5 of 7 Photos: UK party leaders Nicola Sturgeon is the leader of the Scottish National Party, which advocates for Scotland's succession from the United Kingdom. Hide Caption 6 of 7 Photos: UK party leaders Leanne Wood is the leader of the Plaid Cymru Party, which is a political party in Wales that advocates for independence within the European Union. Hide Caption 7 of 7

"We're fighting for a Britain where we reward the hard work of every working person," he said this week, "not just those who get the six figure bonuses in our country."

A total of 650 members of Parliament will be elected, representing constituencies across England, Scotland, Wales and Northern Ireland. Whichever political party has the most members of Parliament elected will be invited by Queen Elizabeth II to form a government. If there's no clear winner, then a minority or coalition government may be formed.

Many observers had predicted no clear winner and suggested there would be days of post-vote, back-room talk to thrash out a power-sharing deal.

But with exit polls pointing toward a more decisive result, British tabloids quickly seized on with their Friday front pages.

The Daily Mirror lamented the projected Conservative victory.

The Sun took a more triumphant tack, with a smiling photo of Cameron front and center.

Tonight's first edition front page: Swinging The Blues pic.twitter.com/O8iga3sH0I — The Sun (@TheSunNewspaper) May 7, 2015

'An electoral tsunami'

I'd treat the exit poll with HUGE caution. I'm hoping for a good night but I think 58 seats is unlikely! #GE15 — Nicola Sturgeon (@NicolaSturgeon) May 7, 2015

Alex Salmond, the party's former leader, said no matter what the final tally is, the result is clear.

"We're seeing an electoral tsunami on a gigantic scale," he told ITN, "and that is a tide flowing with the Scottish National Party."

A big win for the party could accelerate the resurgent momentum toward another Scottish independence referendum in the years to come.

But gaining independence for Scotland isn't the only issue on the Scottish National Party's agenda. They also want to end Britain's nuclear weapons program, which could have an impact on the country's relationship with NATO.

Nicola Sturgeon , its leader and the winner of much acclaim during the campaign, has vowed not to form a pact with the Conservatives, but her past overtures to the Labour Party have been rebuffed.