Boris Johnson has been mocked for saying Theresa May's Brexit strategy would usher in "foreign rule" for the first time since the Battle of Hastings, as he continued his push to kill off her Chequers plan.

The ex-foreign secretary described Ms May's proposals as a "constitutional abomination" and claimed "for the first time since 1066, our leaders were deliberately acquiescing in foreign rule".

Mr Johnson said Irish border proposals would force the UK into becoming a "vassal state" and the talks were on course to end in a "spectacular political car crash", in an article in The Telegraph.

It comes as the prime minister upped her efforts to sell the Chequers blueprint to her party, saying MPs would have to choose between her deal Brexit or no deal at all.

Mr Johnson has thrown his weight behind the rival proposals by the pro-Brexit European Research Group (ERG), led by Jacob Rees-Mogg, where physical checks could be done away from the border, without keeping the UK or Northern Ireland tied to EU customs rules.

He said: "The EU's backstop would leave a border down the Irish sea while the UK's proposal left it "volunteering" to "remain effectively in the customs union and large parts of the single market until Brussels says otherwise.

"Both versions of the backstop are disastrous," he wrote. "One threatens the union; the other version - and its close cousin, Chequers - keep us effectively in the EU, as humiliated rules takers.

"We need to challenge the assumptions of both these Irish backstops, or we are heading full throttle for the ditch with a total write-off of Brexit.

"We are straining at the gnat of the Irish border problem - in fact we haven't even tried to chew the gnat - and we are swallowing the camel of EU membership in all but name."

Labour MP Virendra Sharma, who supports Best for Britain campaign, said Mr Johnson was "Britain's best-know charlatan" and dismissed the comparison to the Norman conquest.

He said: "Chequers is trash - but Johnson neglects to mention how he failed to provide any kind of realistic alternative.

"He would prefer to see chaos on the Irish border than someone else bagging his splash.

"His 1066 reference isn't too far off though. Brexit is like taking an arrow in the eye, and the Brexiteers' constant equivocating won't help. We need a people's vote with the option to stay to sort this out."

In an interview to mark the six-month countdown to Brexit, Ms May told the BBC: "I believe we'll get a good deal, we'll bring that back from the EU negotiations, put that to parliament.

"I think the alternative to that will be not having a deal because a) I don't think the negotiations will have that deal, and b) we're leaving on March 29 2019."

She said the counter-proposal to her Chequers plan is "still a hard border" and her plan was the only way that does not "carve up the United Kingdom".

Ms May said there needs to be "friction-free" movement of goods across the Irish border, without customs or regulatory checks between the UK and EU, after Brexit.

She said that the counter-proposal will not "solve the issue of no hard border by having a hard border 20km inside Ireland".

"The people of Northern Ireland deserve to be listened to in these negotiations by the UK government, as do people elsewhere in this country," she said.

"I want to ensure that as we go forward we have that strong union... Northern Ireland is part of the United Kingdom. They don't want a hard border between Northern Ireland and Ireland.

"The only proposal that's been put forward that delivers on them not having a hard border and ensures that we don't carve up the United Kingdom, is the Chequers plan."

The prime minister said forecasts linked to a no-deal Brexit are "not a prediction", adding: "What is important is how the government responds.

"Under no deal there would be some short-term disruption. It's our job as a government to make sure that we make a success of no deal, just as we make a success of getting a good deal."

Former Lib Dem deputy prime minister Sir Nick Clegg dismissed her claims that there were no other options on the table apart from Chequers or a no-deal Brexit.

"Of all the con tricks we have been subject to in this whole sorry Brexit saga - from the lies in the referendum to the so-called virtues of what is nothing more than an inelegant fudge in Chequers - I think the worst is now to come," he told Today.

"We're now going to be told: 'It's my way or no way' - it's either the Chequers fudge or a sort of cataclysmic cliff edge.

Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Show all 14 1 /14 Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Internal divisions in the Conservative Party have exploded into a bitter public row over Boris Johnson‘s “disgusting” criticism of Theresa May. Some senior Tories furiously denounced the former foreign secretary after he accused the prime minister of having ”wrapped a suicide vest” around Britain Reuters Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Sajid Javid, Home secretary Sajid Javid, the home secretary, rebuked his former cabinet colleague and said: “I think there are much better ways to articulate your differences.” He told the BBC’s Andrew Marr Show that the public wanted politicians to use “measured language” BBC/PA Boris Johnson 'suicide vest' Brexit jibe causes Tory divide But other MPs leapt to Mr Johnson’s defence, as dividing lines ahead of a possible leadership contest begin to take shape. The Uxbridge MP has repeatedly criticised Ms May’s Chequers plan and used a newspaper article on Sunday to suggest it amounted to “wrapping a suicide vest around the British constitution”. His latest salvo at the prime minister prompted immediate condemnation, with one minister publicly vowing to end Mr Johnson’s career over the matter PA Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Alan Duncan, Foreign minister Alan Duncan, a foreign minister who worked in Mr Johnson’s team for two years, wrote on Twitter: “For Boris to say the PM’s view is like that of a suicide bomber is too much. This marks one of the most disgusting moments in modern British politics. “I’m sorry, but this is the political end of Boris Johnson. If it isn’t now, I will make sure it is later.” Getty Boris Johnson 'suicide vest' Brexit jibe causes Tory divide James Brokenshire, Housing secretary Housing secretary James Brokenshire added his voice to the criticism, calling Mr Johnson’s comments ”wrong” He said: “I think he is wrong on this...I think the tone that he has used isn’t right and I think that we just need to be very focused on actually moving forward with the Chequers plan.” AFP/Getty Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Zac Goldsmith But as Tory hostilities spilled over into open public warfare, Richmond Park MP Zac Goldsmith, an ally of Mr Johnson, hit back at Mr Duncan. He wrote: “There are a number of possible motives behind this tweet, but given its author, we can be certain ‘principles’ aren’t one of them.” Getty Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Jacob Rees-Mogg Senior Tory Brexiteer Jacob Rees-Mogg told The Independent he thought Mr Johnson’s “suicide belt” accusation was little more than “a characteristically colourful catchphrase”. He added: “I agree with the sentiment. The criticism of Boris’s wording merely serves to highlight his point. It means more people hear of Boris’s criticism of Chequers and many will agree with him.” Reuters Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Nadine Dorries Nadine Dorries, another Brexit supporter, said Mr Johnson’s opponents were “terrified of his popular appeal”, adding: “Don’t underestimate the vitriol that’ll be directed towards Boris today. He delivered the Leave vote, Remainers and wannabe future PMs hate him.” If Mr Johnson became leader and prime minister he would deliver a “clean and prosperous” Brexit, she said Rex Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Andrew Bridgen Andrew Bridgen said Ms May was to blame for her leadership problems. Asked if Mr Johnson had put a bomb under her leadership, Mr Bridgen said: “I think that Theresa May did that herself when she put forward the Chequers proposals without consulting widely prior to that.” Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Steve Baker, former Brexit minister Steve Baker, the former Brexit minister, warned Ms May the Conservatives faced a "catastrophic split" if she did not jettison her Chequers plan. Mr Baker, who quit the government in July over the scheme, said: “When negotiating, the prime minister needs to demonstrate her intent and also her power to deliver. "If we come out of conference with her hoping to get Chequers through on the back of Labour votes, I think the EU negotiators would probably understand that if that were done, the Tory party would suffer the catastrophic split which thus far we have managed to avoid.” But he insisted he did not want a change in the Conservative leadership, saying Brexiteers did “not want to be in a position of conflict with our own prime minister” Reuters Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Tom Tugendhat The deep divisions on the Tory benches were laid bare as Tom Tugendhat, who chairs the Commons foreign affairs committee and is a possible leadership rival to Mr Johnson, also hit out at the former foreign secretary. Recalling how he encountered a suicide bomber in Afghanistan during his time in the army, Mr Tugendhat told Mr Johnson to “grow up”. He said: “A suicide bomber murdered many in the courtyard of my office in Helmand. The carnage was disgusting, limbs and flesh hanging from trees and bushes. Brave men who stopped him killing me and others died in horrific pain. “Some need to grow up. Comparing the PM to that isn’t happy.” PA Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Alistair Burt Alistair Burt, another Foreign Office minister who worked in Mr Johnson’s team, said: “I’m stunned at the nature of this attack. There is no justification for such an outrageous, inappropriate and hurtful analogy. “If we don’t stop his extraordinary use of language over Brexit, our country might never heal. Again, I say, enough.” AFP/Getty Boris Johnson 'suicide vest' Brexit jibe causes Tory divide It comes amid that Ms May’s former aides drew up a dossier on Mr Johnson’s sexual encounters with the aim of undermining his leadership prospects. The document was compiled in 2016, when the Uxbridge and South Ruislip MP was seen as the main rival to Ms May in her bid to enter No 10. Downing Street and Conservative Campaign Headquaters (CCHQ) both denied having leaked the 4,000 word memo after it was circulated around Westminster AFP/Getty Boris Johnson 'suicide vest' Brexit jibe causes Tory divide Mr Johnson confirmed that his 25-year marriage to wife Marina had ended AP

"The idea that the only thing this country should accept is a fudge or the abyss is not only, I think, an insult to the intelligence of British voters, but it's simply not true."

Meanwhile, reports emerged that EU chief negotiator Michel Barnier is drafting a new "protocol" text that includes the use of technology to minimise checks at the Irish border.

Diplomatic papers seen by The Times said: "The biggest unsolved problem is Northern Ireland.