Boris Johnson will on Wednesday make a “final offer” to Brussels on Brexit, making clear that, if it is not accepted, any further negotiation will not take place until after Britain has left the EU on October 31.

In his first keynote speech to the Conservative Party conference as party leader, he will set out to the party faithful in Manchester details of a “fair and reasonable compromise” that he believes both sides can agree and build upon.

After 70 days of negotiations the fresh legal texts for the new proposed deal will be presented to Brussels on Wednesday.

But No 10 made clear that this would be the final offer.

The plan would mean Northern Ireland remaining in a special relationship with the the EU until 2025, according to reports on Tuesday night.

The Daily Telegraph has also reported that the proposals include the requirement for a regulatory border between the UK and Northern Ireland for four years, as well as customs checks between Northern Ireland and the Irish Republic.

In his speech the Prime Minister will declare: “Voters are desperate for us to focus on their other priorities; what people want, what Leavers want, what Remainers want, what the whole world wants is to move on.”

“That is why we are coming out of the EU on October 31. Let’s get Brexit done; we can, we must and we will,” he will say.

Mr Johnson will also accuse Jeremy Corbyn of wanting to turn 2020 into a year of “chaos and cacophony” with two more referendums.

“A second referendum on Scottish independence, even though the people of Scotland were promised that the 2014 vote would be a ‘once in a generation’ vote and a second referendum on the EU, even though we were promised that the 2016 vote would be a ‘once in a generation’ vote.

“Can you imagine another three years of this? That is the Corbyn agenda; stay in the EU beyond October 31, paying a billion pounds a month for the privilege, followed by years of uncertainty for business and everyone else.”

The PM will argue that, after threeand-a-half years since the EU poll, people are “beginning to feel that they are being taken for fools” and will suspect there are “forces in this country” that simply do not want Brexit delivered at all.

Last night a senior Downing St official said: “The Government is either going to be negotiating a new deal or working on no-deal; nobody will work on delay.

“We will keep fighting to respect the biggest democratic vote in British history. The EU is obliged by EU law only to negotiate with member state governments, they cannot negotiate with Parliament, and this Government will not negotiate delay.”

Yesterday, Mr Johnson accepted postBrexit customs checks might be needed in Northern Ireland but argued they would be “minimal and non-intrusive”.

The PM urged leaders in Brussels, Dublin and Berlin to work with him as the “rubber hits the road” on efforts to strike a deal ahead of the October 31 scheduled Brexit date.

Earlier yesterday, the PM and other senior members of the Government distanced themselves from briefings which suggested the UK had proposed a series of customs posts being built between five and 10 miles from either side of the Irish border.

Yet, in a BBC interview, he acknowledged that some checks could be necessary. “If the EU is going to insist on customs checks as we come out as it is, then we will have to accept that reality. And there will have to be a system for customs checks away from the border.

“Now, we think those checks can be absolutely minimal and non intrusive and won’t involve new infrastructure.”

Mr Johnson accepted proposals for an all-Ireland zone for animal health measures would also “logically imply some more checks down the Irish Sea”, something which could test his political alliance with Northern Ireland’s DUP.

Yet he believed the checks would be “liveable with; provided it’s done in the right way”. Leo Varadkar, the Taoiseach, welcomed London’s insistence that the leaks of the UK discussion paper did not represent its proposals, saying if Mr Johnson had not disowned them, then it would have been “hard evidence of bad faith by the UK Government”.

In a series of TV interviews ahead of his conference speech, Mr Johnson was once again dogged by the controversy surrounding his private life and the allegation that he groped a female journalist 20 years ago. He insisted the claim was “absolutely not true” but admitted he had no memory of the lunch at which the incident allegedly took place.

And the PM also addressed the question about whether he had had a sexual relationship with the US modelturned businesswoman Jennifer Arcuri, declaring: “I can certainly say there was absolutely no question of that at all.”

Elsewhere on the conference floor in Manchester yesterday, Priti Patel pledged a £10 million ringfenced fund to equip up to 60 per cent of police officers in England with Tasers.

The Home Secretary warned criminals: “We are coming after you,” and promised a £20m investment, including a dedicated British Transport Police unit, to aid in identifying and dismantling “county lines” drugs gangs.