Boris Johnson urges Theresa May to give up her Brexit proposals and suggests alternative six-point plan

Former foreign secretary denounces prime minister's plan as 'moral and intellectual humiliation' for country

Boris Johnson has launched an eve of conference attack at Theresa May's Brexit proposals, branding them a national humiliation for Britain and accusing her of seeking to "cheat the electorate".

In a bid to fend off claims he has no ideas of his own he wrote a sprawling 4,600 word newspaper column setting out his six-point plan to what he claimed would be a better Brexit.

It included a call to agree a "super Canada" free trade deal and refusing the EU's plans for the Irish border, with Mr Johnson simply insisting Brussels will agree to something else if pushed.

His broadside heaps pressure on the prime minister who found herself under fire from all wings of her party ahead of the Conservatives' annual gathering in Birmingham over EU withdrawal, her leadership and a lack of vision.

Writing in The Daily Telegraph, Mr Johnson accused the government and civil service of a “pretty invertebrate performance” in negotiations and said there had been “a collapse of will by the British establishment to deliver on the mandate of the people”.

In his column, the former mayor of London said Ms May’s proposal would leave the UK “half-in, half-out” of the European Union and proposed a six-point alternative plan for Brexit.

Mr Johnson said Britain should “chuck Chequers”, Ms May’s Brexit plan, and negotiate a “SuperCanada-type free trade agreement” with the EU.

He called on MPs not to vote to hand over £40bn to the EU without such an agreement.

He wrote: “Overall, the Chequers proposals represent the intellectual error of believing that we can be half-in, half-out: that it is somehow safer and easier for large parts of our national life to remain governed by the EU even though we are no longer in the EU.

“They are in that sense a democratic disaster. There is nothing safe or ‘pragmatic’ in being bound by rules over which we have no say, interpreted by a federalist court.

“The Chequers proposals are the worst of both worlds. They are a moral and intellectual humiliation for this country. It is almost incredible that after two years this should be the opening bid of the British government.”

Mr Johnson also argued for a new withdrawal agreement in which the Irish border question would be settled as part of the deal on the future economic arrangements.

He wrote: “This is the time to get it right. This is the approach that allows this country really to exploit the opportunities of Brexit, to diverge and legislate effectively for the new technologies and businesses in which the UK has such a lead.

“This is an opportunity for the UK to become more dynamic and more successful, and we should not be shy of saying that – and we should recognise that it is exactly this potential our EU partners seek to constrain.”

Mr Johnson concluded his op-ed by issuing a rallying call to loyal Tory voters, writing that ”this is the moment to change the course of the negotiations and do justice to the ambitions and potential of Brexit” and warning “that future generations will not lightly forgive us if we fail”.

His comments come as Jeremy Hunt, the current foreign secretary, called for calm after EU leaders publicly rejected Ms May’s proposal in Salzburg last week. He claimed there was always going to be a point in the negotiations “where everyone was looking into the abyss”.

Mr Hunt also warned the EU and Ms May’s detractors that “underestimating Theresa May is one of the biggest mistakes that you could make right now”.

Tory MP Jacob Rees-Mogg was among the first Brexiteers to rally behind Mr Johnson's dismissal of the prime minister's Chequer's proposal.

Appearing on BBC1's Question Time, he likened the Chequers Brexit plan to Count Dracula, saying it "doesn't have much life in the sunlight".

He said: "I think the negotiations have been badly conducted, I think we have let the European Union make the running in negotiations, we agreed to their establishment of the terms of negotiations and the timetable of the negotiations.

"I think this has not been impressive and I think Chequers is not leaving the EU, it is remaining bound to an EU rule-book which is interpreted by the European Court of Justice and the EU's rejected it anyway.

"So Chequers may not not even be a dying duck, it may be slightly more Count Dracula in that it seems to get up at night and walk abroad, but it doesn't seem to have much life in the sunlight."

Layla Moran, a Liberal Democrat MP who also appeared on the programme, said Mr Johnson’s Brexit plan was “a half baked, sloppy rant” and “more of a joke than his stint as foreign secretary”.

She said: ”The blue on blue in-fighting has already kicked off ahead of Tory conference. But while Johnson is being paid hundreds of thousands to belch out the first thing that comes to mind on page, there are businesses up and down the country wondering whether they’ll still exist after Brexit.

“It’s a disgrace that he can’t take the most important decision facing this generation seriously. This is why he’s known Britain’s best-paid charlatan.”

Although just six months remain before the UK is scheduled to leave the EU on 29 March, 2019, Ms May has failed to secure a divorce deal with the EU and rebels within her own party have threatened to vote against any deal she makes.

Mr Johnson, who was one of the most prominent campaigners for Brexit during the 2016 referendum, resigned as foreign secretary in July over a disagreement with Ms May’s Brexit proposals, which he condemned in his 4,600-word article for The Telegraph as “enforced vassalage”.

Ms May has repeatedly claimed her Brexit proposals are the only viable option.

Earlier this week, she ruled out a general election before Britain leaves the EU, saying it would not be in the national interest, and staunchly rejected the possibility of a second Brexit referendum.