BORIS Johnson has again declined to discuss in detail a late-night quarrel at his home, saying it was "simply unfair" to "drag" his loved ones into the political arena.

The Tory leadership frontrunner also called for "creative ambiguity" over the £39 billion cost of the UK's Brexit divorce deal, suggesting this could break the deadlock, in an interview with the BBC's Laura Kuenssberg.

The former Vote Leave leader, who hopes to become prime minister, also called for a "commonsensical" no-deal Brexit to be left on the table to allow the "incubus" to be "pitchforked off the back of British politics".

It was the first in a flurry of broadcast interviews and visits in the South East planned for Tuesday, a spokesman told the Press Association, adding: "We're definitely stepping it up."

The shift in strategy comes after their normally high-profile candidate was dubbed "a coward" by leadership rival Jeremy Hunt for refusing to take part in televised debates and ducking questions about a row in his partner's flat in the early hours of Friday.

Mr Johnson had held out for three days on making any statement about the spat, which saw police called by worried neighbours after his partner was heard screaming and shouting "get off me".

Asked what happened that night by Kuenssberg, Mr Johnson said he did not want to "drag" his family and loved ones into the political spotlight.

He said: "I... would love to tell you about all sorts of things, Laura, but I've made it a rule over many, many years - and I think you've interviewed me loads of times - I do not talk about stuff involving my family, my loved ones.

"And there's a very good reason for that. That is that, if you do, you drag them into things that... in a way that is not fair on them."

Mr Johnson was asked whether privacy meant more to him than public trust and responded: "Yes I get that, I totally get that.

"But my key point though is that the minute you start talking about your family or your loved ones, you involve them in a debate that is it is simply unfair on them."

The issue of a photograph of the couple at the weekend that emerged on Monday was raised, with Kuenssberg suggesting the former mayor of London could be "trying to have this both ways".

Mr Johnson dodged the question, saying "I just do not go into this stuff" and referred to "innumerable statements I gave when I was mayor".

He said: "Actually, I think what people want to know is what is going on with this guy, does he - when it comes to trust, when it comes to character, all those things - does he deliver what he says he's going to deliver?

"And that is the key thing."

On Brexit, Mr Johnson called on the UK to "abandon the defeatism and negativity" as he claimed the route out of the impasse was "to prepare confidently and seriously for a WTO (World Trade Organisation) or no-deal outcome".

The Conservative MP claimed he would be able get such a no-deal Brexit through Parliament.

"I think that MPs on both sides of the House also understand that they will face mortal retribution from the electorate unless we get on and do it," he said.

"People want to get this thing done. They want to get it done sensibly... and they want to get it done in a way that allows us to move on which is why I think people are yearning, they're yearning for this great incubus to be pitchforked off the back of British politics."

The former foreign secretary criticised the UK negotiating team for being the "authors of our own incarceration" in creating the backstop to prevent a hard border on the island of Ireland.

Suggesting he would dump the negotiators, Mr Johnson said: "Change the approach of the UK negotiators and you have a very different outcome."

But when picked up on what would enable to UK to avoid any backstop, Mr Johnson could not name an existing technology.

He also insisted he would have time to come up with an alternative to the backstop during an implementation period - despite this being part of Theresa May's deal, which he had earlier dismissed as "dead".

Justice Secretary David Gauke, who backed Rory Stewart in the race, tweeted: "Can we all agree on the following?

"The implementation period is one element of the withdrawal agreement.

"Without the withdrawal agreement, no implementation period has been agreed.

"Leaving without a deal on 31 October means leaving without an implementation period."