Jo Swinson has pledged to take on the forces of nationalism and populism and “do whatever it takes to stop Brexit,” in her first speech as the new leader of the Liberal Democrats.

The cheers were so loud when Sal Brinton, the Liberal Democrat President, confirmed the Scot’s win that she was only able to read out the first word “forty”.

The numbers were 47,997 for Ms Swinson to 28,021 for Sir Ed Davey on a turnout of 72 per cent among the 107,000 party members.

After several weeks of criss-crossing Britain at party hustings, Ms Swinson beat her challenger comfortably, polling 63 per cent of the vote.

Loyal party supporters were crammed into a cabaret club on London’s Victoria Embankment for the result with standing room only for many; a victory rally was due to be held at the venue later on.

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In an at times emotional speech – her voice broke when she mentioned her late father – the 39-year-old MP for East Dunbartonshire, who becomes her party’s first female leader, said the Lib Dems faced an historic moment, having been boosted by gains in the local English and European elections. So much so, that the party is now regularly polling over 20 per cent.

In a wide appeal to the electorate, she said: “If you are tired of a politics that doesn’t include people like you, whether that’s because of your gender, disability or the colour of your skin, your accent, age, or who you love, then join us.

“The urgency of this moment in our country’s history needs us to think and act even bigger. Whether it’s Brexit or the climate crisis, we don’t have the luxury to wait 15 or 20 years for us to rebuild our seats in Parliament.”

Ms Swinson insisted this was the time for working together, not the time for tribalism, in order to grow the liberal movement and “take on nationalism and populism”.

Indeed, as rumours reverberate around Westminster that more MPs could soon be defecting to the Lib Dems, the party leader directly addressed those in other parties who shared Lib Dem values.

The Herald: Camley's Cartoon: Swinson wins Lib Dem leadership contest.Camley's Cartoon: Swinson wins Lib Dem leadership contest.

“If you believe our country deserves better, that we can stop Brexit, that we can stop Johnson, Farage and Corbyn, then work with us, join us. My door is always open.

“And to everyone watching this right now. If you think that our country is headed in the wrong direction and you want to change that, you need to act too. Shouting at the television is not enough. You need to join us,” she declared.

During her speech Ms Swinson paid tribute to her predecessors in the role Sir Vince Cable, who was sitting in the audience, Tim Farron, Sir Nick Clegg and Lord Menzies Campbell.

She spoke about the division and nastiness unleashed by the 2016 EU referendum but she had seen it before in the 2014 Scottish independence poll.

“Sandra, one of my local members, had a brick thrown through her window, which displayed a pro-UK poster. On the campaign trail, an elderly woman pulled up her coat sleeve to show the pro-UK campaign sticker on the inside of her wrist – such was her fear of wearing it on her jacket. A mob of hundreds outside the BBC, demanding Nick Robinson be sacked. Twitter trolls, fake news, demonising journalists, we saw it in Scotland first. And since then, that harsh, hostile politics has become the new normal.”

The Lib Dem leader launched stinging attacks on Nigel Farage, Jeremy Corbyn and Boris Johnson.

She won applause from the audience when she declared: “I rage when Boris Johnson is more interested in sucking up to Donald Trump than standing up for British values of decency, equality, and respect.”

Ms Swinson is expected to visit Brecon and Radnor shortly to support her party’s campaign in the local by-election on August 1. Party sources say they are confident they can retake the Welsh seat by overturning the Tories’ 8,038 majority.

After her leadership victory, Alistair Carmichael, the MP for Orkney and Shetland who voted for Ms Swinson, said he was absolutely delighted by the result.

“Either of the two candidates would have been excellent leaders but what you have seen there is a woman with passion and conviction, able to take the party onto the next stage. There are no ceilings to her ambition for the party. That is something probably that the Liberal Democrats will be the last people to understand. The rest of the world is getting that message now and Jo will be an excellent carrier for it.”

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Another Swinson supporter, Christine Jardine, the MP for Edinburgh West, said: “What you heard today is someone who will take the SNP on, and understands what it is we need in Scotland.

“We are the only party that will stand up for both the UK and the EU; that’s what the people in Scotland want. They want both Unions. Jo was absolutely clear that both populism and nationalism have been bad for this country, they’re damaging this country, and she’s going to fight to put an end to that.”