BORIS Johnson says he is "cautiously optimistic" of getting a new Brexit deal with the EU as he prepares to hold talks with Jean-Claude Juncker next week.

However, No 10 played down the prospect of a dramatic breakthrough at Monday's talks with the outgoing European Commission President and Michel Barnier, the EU's chief negotiator, which are due to take place over lunch in Luxembourg.

The Prime Minister, during a speech to the Convention of the North in Rotherham, was heckled with the man shouting: "Get back to Parliament." Mr Johnson has controversially suspended Westminster for five weeks.

In his speech, he spoke about handing power to northern leaders in Rotherham, saying: "I know the transformative potential of local accountable leadership, someone with the power to sort out what matters most to local people."

But, interrupting the broadcast being televised live, the heckler shouted: "Like our MPs, Boris?"

"Yes, indeed," Mr Johnson replied.

The heckler continued: "Maybe get back to Parliament. Yeah? Why are you not with them in Parliament sorting out the mess that you have created? Why don't you sort it out, Boris?"

The PM said: "I'm very happy to get back to Parliament very soon, but what we want to see in this region is towns and communities able to represent that gentlemen and sort out his needs."

Later, when asked how the talks with Brussels, Mr Johnson said good progress was being made and that he was "cautiously optimistic" a new deal could be done.

Earlier, during a trip to a busy marketplace in Doncaster, he joked with one lobster seller: "We've got to take a few claws out of that Withdrawal Agreement," adding: “We’re going to get a deal. That's the plan, anyway. And if we don't, we're coming out on October 31. That's what we're going to do. Here we go, that's democracy."

He told another shopper: “We'll get you out, we'll get us out.”

As Northern Ireland’s Democratic Unionists dismissed suggestions that they were softening on the key issue of the Irish backstop, Leo Varadkar, the Taoiseach warned the gap between the two sides on it remained "very wide".

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He told RTE radio: "We have always said we would be willing to look at alternative arrangements but what we're seeing falls far short.

“We are exploring what is possible. The gap is very wide but we will fight for and work for a deal until the last moment; but not at any cost," he added.

And the Irish PM warned some checks might have to be placed on the border in the event of a no-deal Brexit.

After announcing Mr Johnson's trip to Luxembourg - it will be the PM's first meeting with Mr Juncker since taking over in Downing St in July - a senior No 10 source played down the prospect of an imminent breakthrough, saying: “The PM is working hard to get a deal and we have been putting forward ideas but there is a long way to go."

The talks were described as part of the ongoing engagement with key figures; the PM has already had face-to-face meetings with Germany’s Angela Merkel, France’s Emmanuel Macron, Mr Varadkar and Donald Tusk, the outgoing European Council President.

Meanwhile, Arlene Foster, the DUP leader, dismissed reports that her party was about to offer the UK Government a lifeline to help it unlock a Brexit deal.

It was claimed the Northern Irish party had agreed to shift its red lines on Brexit, saying it could accept Northern Ireland abiding by some EU rules post-Brexit as part of a new deal to replace the Irish backstop.

As the possibility of an all-Ireland food zone was raised, it was also suggested the province’s biggest party had privately said it would drop its objection to regulatory checks in the Irish Sea, something it had previously insisted was unacceptable since it would separate Northern Ireland politically and economically from the UK mainland.

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In return for such a concession, Brussels was said to be prepared to abandon its insistence on Northern Ireland remaining in a customs union with the EU.

However, Ms Foster insisted that, as previously indicated, any moves which did make Northern Ireland different from the rest of the UK would be totally unacceptable to the party.

"The UK must leave as one nation,” she declared, tweeting: “We are keen to see a sensible deal but not one that divides the internal market of the UK. We will not support any arrangements that create a barrier to East West trade."

She added: "Anonymous sources lead to nonsense stories."

Sammy Wilson ,the party’s spokesman, was equally dismissive that the party was softening its stance yet he did day he had detected a different tone in talks between London and Dublin.

He told BBC Radio 4's Today programme: "There was a different attitude in the talks between the Prime Minister and the Taoiseach at the beginning of the week and there seemed to be less rhetoric at those discussions from what there had been in the past. And I suppose that's progress."

In a separate development, Mr Johnson has been warned against breaking the law over Brexit by John Bercow, who vowed that "creativity" in Parliament would scupper a no-deal exit.

The comments from the Commons Speaker drew sharp criticism from prominent Tory Brexiteer Sir Bernard Jenkin, who said Mr Bercow had launched a personal attack on the PM.

The Speaker’s intervention came as Michel Barnier said there was "no reason to be optimistic" that a new agreement could be brokered before the PM's deadline to ask for a delay.

The EU’s chief negotiator told political leaders in the European Parliament on Thursday that he was unable to say whether contacts with the UK Government would result in a deal by mid-October.

The PM is legally bound to ask Brussels for an extension to Article 50 if he cannot get MPs to back a deal by October 19, after Parliament approved legislation designed to prevent a no-deal. But Mr Johnson has been adamant he will not do it, saying he would rather be “dead in a ditch” than ask Brussels for a further Brexit extension.

Mr Barnier's warning came after the PM was forced to deny lying to the Queen in order to secure his five-week suspension of Parliament as the Hallowe'en departure deadline looms.

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In a London speech, the outgoing Speaker said the so-called Benn Act enforcing the extension meant the only possible Brexit outcome was one approved by Parliament.

Mr Bercow said it was "astonishing" that anyone had entertained the idea that the PM could disobey the law. He compared refusing to ask for a delay in "what one might regard as the noble end" of Brexit to a bank robber insisting they would give their loot to charity.

If the Government came close to disobeying the Act, the Speaker said Parliament "would want to cut off such a possibility and do so forcefully".

He explained: "If that demands additional procedural creativity in order to come to pass, it is a racing certainty that this will happen, and that neither the limitations of the existing rule book nor the ticking of the clock will stop it doing so.”

But Sir Bernard attacked Mr Bercow's remarks, telling the BBC: "The office of Speaker has become irretrievably politicised and radicalised.

"It would have been unthinkable 10 or 15 years ago for the Speaker of the House of Commons to launch a personal attack on the Prime Minister like this."

Sir Bernard said MPs should now review the role of Speaker.

He added: "For one individual in what is now a contested, televised, very public and controversial position to have so much unregulated, untrammelled power is something, I think, that the House of Commons is going to have to look at."

Mr Johnson would not have to ask for an extension to January 31 if MPs approved a deal or no-deal under the Benn Act, which was pushed through Parliament by opposition MPs and Tory rebels.

But Mr Barnier, in a speech to MEPs, suggested that negotiating a new Withdrawal Agreement remained uncertain despite discussions between Mr Johnson's team and the EU.

"I cannot tell you objectively whether contacts with the Government of Mr Johnson will be able to reach an agreement by mid-October.

"While we have previously reached an agreement, as far as we can speak, we have no reason to be optimistic."

The developments came after the PM "absolutely" denied lying to the Queen to get the suspension of Parliament.

Scotland's highest civil court ruled on Wednesday that the prorogation was unlawful because it was obtained for the "improper purpose of stymying Parliament".

Mr Johnson said the High Court in England had taken the opposite view to the Court of Session in Edinburgh and that the case would now be decided in the Supreme Court.

He also insisted he was "very hopeful" that he could secure a deal by the EU summit starting on October 17.

Meanwhile, the full opinions from the judges at the Edinburgh court emerged on Thursday evening.

Judge Lord Carloway said the "true reason" for the suspension was to reduce time for "parliamentary scrutiny of Brexit" in a "clandestine manner".

The matter will now be heard by the UK Supreme Court on Tuesday with a judgement expected by the end of the week. If it were to concur with the Scottish judges’ ruling, then there would be enormous pressure on Mr Johnson to resign; there may even be calls for him to be prosecuted.