Boris Johnson row: Favourite to be next UK Prime Minister under fire as top Conservatives raise fears
Leadership campaign falters as he refuses to respond to questions at hustings about late-night argument with Carrie Symonds
Boris Johnson remains under pressure to answer questions about police being called to his partner's home, with a Conservative grandee accusing him of a "lack of judgment" over his refusal to comment on the incident.
The favourite to be the next UK Prime Minister declined to explain to Conservative grassroots what went on at the south London flat in the early hours of Friday morning, saying the party faithful did not want "to hear about that kind of thing".
Mr Johnson's campaign for Number 10 was rocked by the revelations that officers were called to the home he shares with partner Carrie Symonds by a neighbour who claimed to have been "frightened and concerned" after hearing shouting, "a loud scream" and banging coming from the property.
A poll carried out after the reports emerged suggested Mr Johnson's support among Tory voters had dropped by more than half, while among the general electorate it indicated he had slipped into second place behind rival Jeremy Hunt.
The Foreign Secretary ramped up his challenge to Mr Johnson on Saturday, saying in an open letter that their "character" was being tested in the final stage of the leadership race and "scrutiny can be uncomfortable".
When asked at the hustings about the incident, Mr Johnson said people "are entitled to ask about me and my determination, my character and what I want to do for the country".
But he would not elaborate on the police visit, preferring to talk about his time as mayor of London instead.
Moderator Iain Dale drew heckles from some in the crowd when he asked Mr Johnson whether a person's private life had any bearing on someone's ability to discharge the office of Prime Minister.
"Don't boo the great man," Mr Johnson said, but Mr Dale suggested he was "completely avoiding" the question.
Tory grandee Sir Malcolm Rifkind told BBC Radio 5 Live: "If you are a candidate to be prime minister and the police have been called to your house - fairly or unfairly - the fact is there was a police visit. You don't just say 'no comment'.
"That implies you may have something you don't want to disclose."
Sir Malcolm, who indicated he would back Mr Hunt in the race, added: "It was a lack of judgment to refuse to even make a short comment. All he could have said, quite reasonably, would have been that in all relationships there are occasionally outbursts of anger and disagreement."
The former foreign secretary rejected a suggestion that Mr Johnson should be allowed to draw a distinction between his private and public life.
"I'm sorry, you don't have that sort of private life if you're asking people to choose you to be their prime minister," Sir Malcolm said.
"Of course there are certain things that are utterly personal, but it's rather like Michael Gove being asked if he took cocaine."
On Saturday night the neighbour who rang the Metropolitan Police went public after suggestions that his recording of the row had been leaked to The Guardian with political intent.
Tom Penn said the allegations were "bizarre and fictitious", explaining in a statement to the paper that he dialled 999 after hearing shouting coming from his neighbour's flat.
"It was loud enough and angry enough that I felt frightened and concerned for the welfare of those involved, so I went inside my own home, closed the door, and pressed record on the voice memos app on my phone," the 29-year-old playwright said.
"After a loud scream and banging, followed by silence, I ran upstairs, and with my wife agreed that we should check on our neighbours.
"I knocked three times at their front door, but there was no response. I went back upstairs into my flat, and we agreed that we should call the police."
The revelations threw Mr Johnson's leadership campaign into chaos and a poll by Survation for the Mail on Sunday suggested it had struck a blow to his dominant position in the race.
Two surveys suggested Mr Johnson's lead over Mr Hunt among Conservative voters had been cut from 27 points to 11, while among all respondents Mr Hunt was ahead on 32% with Mr Johnson on 29%.
Mr Johnson insisted at the hustings he was the one to "get Brexit done" and put his record at City Hall at the heart of his pitch.
Meanwhile Mr Hunt, who will visit Scotland on Sunday, revealed a pledge to exempt hundreds of thousands of firms from business rates if he becomes prime minister.
The rivals are battling to win the support of 160,000 Tory party members who will choose their next leader, and the prime minister, in July.
Following reports of dirty tricks by Tory MPs in previous rounds of the contest, it has been reported that Tory party chiefs have been warned that police will need to be called in if there are any claims of intimidation of voters in the final stage.
According to the Sunday Mirror, David Morris, the Tory MP for Morecambe and Lunesdale who sits on the Commons Administration Committee, told party chairman Brandon Lewis that an MP said they had been threatened with a vote of no confidence if they did not back Mr Johnson.
"This is intimidatory behaviour. These are very serious tactics and could lead to criminal prosecutions. I want a categorical assurance these kinds of activities will not continue," Mr Morris is said to have written.