Tory leadership debate - live: Boris Johnson challenged on ‘letterbox’ comments, as candidates quizzed on Brexit, tax cuts and climate change

The first question of tonight's hustings comes from a BBC viewer in Norwich, who says he voted for the Brexit Party in last month's European elections. He asks candidates to explain how they will get their Brexit plan through parliament by 31 October.

Boris Johnson answers first, saying the UK must leave the EU by 31 October or face "a catastrophic loss of confidence in politics". He says politicians must act "maturely and soberly in the interests of democracy and get this thing done". He doesn't actually answer the question.

Jeremy Hunt says he would "take a bit longer" if a deal was within sight but would be happy to opt for a no-deal Brexit rather than ask for another lengthy delay.

Michael Gove agrees with Jeremy Hunt. He says he was the first candidate to argue for Leave but that it would be sensible to delay for "an extra 24 or 48 hours to get it over the line" if a deal is in sight.

Sajid Javid says politicians have "failed to act on the intructions" given to them by the electorate. He says it is "fundamental" that the UK leaves the EU by 31 October and that Mr Hunt and Mr Gove are wrong to consider a further delay.

Rory Stewart says MPs have to be honest and admit it will not be possible to negotiate a new deal by 31 October. He says trying to negotiate a new deal would mean a delay of months or years and that candidates must be honest about this. He says he won't pledge to negotiate a new deal but tells his rivals "let's get on with it" by passing the current deal.

Disagreeing with Rory Stewart, Michael Gove says "we can't present the same cold porridge" by supporting the Brexit deal that MPs have already rejected three times. He says he would accept a short delay but no longer than the end of 2019.

Boris Johnson says negotiating a new deal by 31 October is "eminently feasible". Jeremy Hunt pushes him on what he would do if a deal was in sight but extra time is needed. He says nobody wants "a disorderly no deal" but but there is "wide consensus that we must get out on 31 October...and that is the way that we will get the deal we need".

Sajid Javid agrees with Boris Johnson that a hard deadline is needed to "focus minds" and also insists that a new deal can be negotiated before 31 October. He says "anyone who has ever negotiated anything" knows this.

The next question comes from a member of the public who raises the prospect of a damaging no-deal exit and asks why the candidates are even contemplating it.

Michael Gove admits no deal would cause "economic turbulence" but says "we need to ensure that we are ready for whatever comes...and that we make sure we put our democracy first". He adds: "We're a great country. We can get through it."

Rory Stewart asks the other candidates how they would deliver no deal without the consent of parliament, given MPs are opposed to it. No answer is immediately forthcoming. Boris Johnson simply says there has been a lot of preparation for no deal, while Sajid Javid says preparations haven't been good enough. Appearing serious about leaving without a deal is the only way to secure a good deal, he says.

Jeremy Hunt says that taking no deal off the table will mean Brexit is delayed indefinitely. He echoes Mr Javid, saying no deal must remain an option in order to secure a better deal, "but it should only be a very, very last resort".

Rory Stewart promises that if he is prime minister, "there would never be no deal...it is unnecessary and damaging and it is not even a credible threat".

The next question comes from a voter in Northern Ireland. It is about the Northern Irish border and how candidates will keep it open after Brexit.

Jeremy Hunt says EU leaders are clear that the UK must come forward with a solution that will work. He says the Northern Ireland backstop will never get through parliament. Instead, he claims the border can be kept open using technology.

Sajid Javid gives a similar answer, insisting theHome Office has found it is "perfectly possible to have an open border using existing technology". He says he will negotiate a time-limit on the backstop, claiming the Irish government would be willing to contemplate this. That might be news to Dublin...

Boris Johnson claims the question of how the Northern Irish border can be kept open can be negotiated during the implementation period (which of course will only happen if MPs pass a Brexit deal...). He claims the EU would agree to an implementation period even if there is no withdrawal agreement.

Rory Stewart presses Mr Johnson on the detail. The former foreign secretary claims there will be no tariffs or quotas on goods travelling between the UK and Ireland because he will negotiate a free trade agreement.

Michael Gove chips in to say that restoring the devolved government in Northern Ireland is key. He says he would "supercharge work on alternative arrangements" so that the backstop could be replaced.

Rory Stewart says the EU has made clear it will not renegotiate the Withdrawal Agreement. Of his rival candidates, he says: "Every single one of these people is not explaining how they're going to do it."

The next question is about how candidates will "lift the tax burden on the working classes".

Sajid Javid answers first, saying the Brexit vote was about more than leaving the EU. "There is too much pressure on working people today," he says, adding that he would prioritise tax cuts for working people.

Jeremy Hunt says he would "reduce the tax burden on the lowest paid" and that there should be no tax on the first £1,000 that people earn each month. He says cutting business taxes will boost economic growth and this will allow him to slash taxes for working people. He indirectly attacks Boris Johnson, saying the Tories must never prioritise tax cuts for the wealthy.

Boris Johnson says that, as mayor of London, he expanded the London Living Wage. He says he would lift the threshold of national insurance for low-paid people but insists it is "relevant" and "very sensible" to have a debate about higher rates of tax. He says no Conservative should oppose his sugggestion that people who are nurses, senior teachers and police inspectors should pay less tax.

Michael Gove says he is the candidate who is "most pro-working people". He says he would focus on replacing VAT and would reduce business rates for small businesses. He says Mr Johnson is making a mistake in focusing on tax cuts for people "who earn what MPs earn and what millionaires earn", adding: "I think that is wrong. I went into politics to help the very poorest in our society."