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 exclusive with the BBC’s political editor 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”.

Whaling in Japan
Carrie Symonds (John Stillwell/PA)

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 answer 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”.

Tory leadership race
Media outside Boris Johnson’s home in south London (Yui Mok/PA)

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 that emerged at the weekend was raised, with Kuenssberg suggesting the former mayor of London could be “trying to have this both ways”.

Laura Kuenssberg (PA/Dominic Lipinski)

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.”

EU referendum
Boris Johnson on the Vote Leave tour (Stefan Rousseau/PA)

Kuenssberg agreed trust was key and suggested the Tory membership would be looking at his record when deciding whether to vote for him and warned: “There are plenty of people even in the Conservative Party who worry that you do not stick to what you promise.”

Mr Johnson replied: “Well I think they’re talking absolute nonsense.

“When I was mayor, when I became mayor of London, when we said we would do something, we… delivered not just X but X plus 10.”