Vince Cable calls for 'political adults' to work together against hard Brexit

Britain needs “political adults” to work together to halt a damaging Brexit, Vince Cable will tell the Liberal Democrat conference on Tuesday, urging moderate Conservatives and Labour MPs to work with his party.

Cable will also call on the Labour leader, Jeremy Corbyn, to listen to the many pro-EU voters who backed him in June. “He would do better to get off the fence and refurbish his revolutionary credentials. Jeremy, join us in the Anti-Brexit People’s Liberation Front,” he will say in his first keynote speech as Lib Dem leader.

In a speech in which the 74-year-old former business secretary will argue that his age and political experience are a tactical advantage, Cable will say it is possible to preserve the UK’s place in the single market and customs by working cross-party.

“What the people want, what the country desperately needs is some political adults,” he will say. “Fortunately we are not alone. There are some sensible grownups in the Conservative party and the Labour party and the Greens.

“And beyond them are millions of people deeply worried about what is happening. We have to put aside tribal differences and work alongside like-minded people to keep the single market and customs union, essential for trade and jobs.”

He will attack senior politician including Boris Johnson and David Cameron, calling the EU referendum battle “a fraudulent and frivolous campaign led by two groups of silly public school boys reliving their dormitory pillow fights” and the Brexit negotiators “people who would struggle to get their heads around a toddler’s Lego set”.

Cable’s speech will come after Nick Clegg described being in a coalition with the Conservatives as extremely tough by the end of the parliament, likening working with Cameron to “being in a cage with a demented gorilla”.

He said the former prime minister was constantly being pulled to the right by the time of the election in 2015, “trying to find ways of satisfying loopy people like Jacob Rees-Mogg”. Clegg said he was still in touch with some Conservative coalition ministers, including Cameron, George Osborne and current chancellor Philip Hammond. But he said relations had significantly deteriorated with others, recalling how Michael Gove had once “locked himself in the loo” to avoid seeing Lib Dem minister David Laws.

Though Cable will urge cross-party cooperation to limit a hard Brexit, he will also reassert the Lib Dems’ commitment to keeping the UK in the EU, calling them “the party of remain”.

Party sources said the speech was unlikely to depart significantly from the former leader Tim Farron’s flagship policy of offering a referendum on the final Brexit deal, which delivered only limited gains for the Lib Dems at the June election and which put them at odds with many voters in their former heartlands in south-west England.

Cable is understood to be keen to place the emphasis on the economic costs of leaving the EU – the policy area he can speak on with authority.

Cable will say any new referendum must not be seen as a second running of the June 2016 vote. “Let me be clear: this is not a call for a re-run – a second referendum – on Brexit,” he will say. “It is a call for a first referendum on the facts, when we know what Brexit means.”

Cable will say his party is likely to be “denounced as traitors and saboteurs” along with supreme court judges. “But if the definition of sabotage is fighting to protect British jobs, public services, the environment and civil liberties then I am a proud saboteur,” he will say.

“Brexiteers will say ‘we have already voted to leave. How dare you flout democracy.’ It is actually quite difficult to follow the argument. It seems to go that consulting the public – having a vote – is undemocratic.”

Over the course of the four-day conference in Bournemouth, Cable has sought to re-establish the Lib Dems as a credible party of government, telling the Observer and the BBC he believed it was possible for the Lib Dems to win a Commons majority and for him to become the next prime minister.

But the Lib Dem education spokeswoman, Layla Moran, the newly elected MP for Oxford West and Abingdon, told a party fringe meeting she did not think that ambition was realistic in the short term.

Moran said talk of Cable as prime minister was “good fun” but the focus should be on “distinctive positions” and new policies.

“It’s not just the leadership, there is a portion of the wider party that still kind of believes this too, that somehow we are going to go back into government at any moment,” she said. “And I think we need to kind of accept we’re not.”