Liberal Democrat leader Jo Swinson has warned Boris Johnson that being a woman will not stop her from toppling him as Prime Minister.

In hard-hitting comments, the East Dunbartonshire MP told a rejuvenated party that the Conservative Party leader would find out that being a female was not a “weakness”.

She told members in Bournemouth in her closing speech: “Boris Johnson’s insults of choice are rather revealing – big girl’s blouse, girly swot.

“But let me tell you conference, if he thinks being a woman is somehow a weakness, he’s about to find out: it is not.”

The 39-year-old compared Mr Johnson to a dictator for suspending Parliament and sacking 21 Tory MPs for rebelling against him.

In a scathing attack on the PM, she said: “Silencing critics, purging opponents, ignoring the law – for someone who proclaims to hate socialist dictators, he’s doing a pretty good impression of one.”

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Lib Dem members watch Jo Swinson give the closing conference speech (Jonathan Brady/PA)

Watched on by her mother Annette and husband Duncan Hames, a former MP, Ms Swinson – in a wide-ranging speech – told members that they must no longer view themselves as bit players in Westminster.

The party currently has 18 MPs – boosted by six defections this year alone – meaning it would need more than 300 additional seats to secure a majority in the House of Commons.

Yet the former minister has continually dismissed calls to join in a coalition with either Mr Johnson or Labour’s Jeremy Corbyn after the next general election, saying that neither are “fit” to lead the country.

Instead, she told conference: “I am standing here as your candidate for prime minister.”

Members gave her multiple standing ovations as she told them: “We can win, we must win. And to do so, we must build the biggest liberal movement this country has ever seen.

“We cannot be satisfied with a place on the fringes of British politics, narrow and pure, small and irrelevant.

“Only a Liberal Democrat government can deliver the fair, inclusive and open future that we deserve.”

The party this week committed to cancelling Brexit without a referendum if Ms Swinson is elected to Downing Street.

“There is no Brexit that will be good for our country,” she said.

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Jo Swinson said Boris Johnson was acting like a dictator after sacking 21 Tory MPs (Stefan Rousseau/PA)

Ms Swinson predicted that Brexit would “hurt” jobs and the British economy, while pouring scorn on the PM’s likelihood of securing a deal with the European Union.

Referring to his decision to pull out of a press conference in Luxembourg on Monday due to fears of not being heard over protests, she said: “He claims he can negotiate a Brexit deal in a month.

“I wouldn’t hold much hope – yesterday he failed to negotiate where to have a press conference.”

She criticised the millions spent on preparing for a no-deal exit as “sickening” and compared leaving without an agreement as equivalent to “burning your own house down”.

“You might have insurance, but you’re still going to lose all your stuff,” she explained.

Giving the final speech of the four-day gathering, she also confirmed the Lib Dems would introduce a budget based on wellbeing if it wins power.

The wellbeing budget would see government policy tested to determine how much happier it would make UK citizens.

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Jo Swinson’s husband Duncan Hames and mother Annette watch her make the Lib Dem conference keynote speech (Jonathan Brady/PA)

To tackle climate change, she committed the party to bringing in climate risk reporting for businesses, reviving the Green Investment Bank scrapped by the Tories and putting together a citizens’ assembly on climate change to produce ideas for tackling the threat of global warming.

She also called for a public health approach to cutting knife crime, investing in schools and hospitals – a model based on Glasgow, where the city council reduced the murder rate by 70%.

Opening up about her personal motivation for taking the job of Lib Dem leader, the mother of two said she had been inspired to make a difference for her children, Andrew, aged one, and Gabriel, three.

“People often say to me, how do you do this with two young children,” she said.

“And of course, it is hard. Parenting is never easy.

“But they are why I am standing here. If I can do something to change the future, how could I not do this? There is too much at stake.”