Whatever happened in Carrie Symonds’ flat, Boris Johnson is still set to become prime minister

A fierce temper is not a disqualification from office. I remember being surprised by the mildness of the reaction of public opinion to stories about Gordon Brown bullying his staff

Boris Johnson’s campaign to become prime minister has suffered a setback, but he will probably plough on to a slightly less overwhelming victory than he otherwise would have won.

Conservative Party members are likely to take a liberal view of his row with his girlfriend, who was a key member of his campaign team. They may not all be as hyper-partisan as some of Johnson’s supporters, who blamed the neighbours for calling the police, but their party loyalties make it likely that they will filter what they want to hear from the shouting.

Some of them may be disappointed to discover that the jovial polymath has another side to his character. What was surprising to most people was not that Johnson and Carrie Symonds had an argument, but that our likely prime minister has a temper.

Sonia Purnell, who worked in the Telegraph office in Brussels with Johnson and later wrote a biography of him, said on the Today programme this morning that his temper was “quite frightening” and “I don’t want to see it again”.

But a fierce temper is not a disqualification from office. I remember being surprised by the mildness of the reaction of public opinion to stories about Gordon Brown bullying his staff. Towards the end of his time as prime minister, in February 2010, the National Anti-bullying Helpline said that four people who worked in Brown’s office had contacted them.

Yet a YouGov poll found that 43 per cent thought the reports that Brown bullied his staff were “exaggerated”. Another 22 per cent thought they were “true – but I’d rather have a prime minister who is passionate and sometimes goes over the top than someone who lacks passion”. Only 21 per cent thought they were “true – Mr Brown’s behaviour is outrageous, and he is not fit to be prime minister”.

I suspect that public opinion would take a similar view of Johnson, and that Tory party members would be even more likely to opt for the “passionate” interpretation. My view is that there are many reasons for thinking that Johnson would be a disastrous prime minister, and the state of his relationship is some way down the list.

Indeed, any member of the Conservative Party who is considering how to cast their vote should have listened not just to Sonia Purnell on the Today programme, but to Dominic Grieve.

The former attorney general seemed uncomfortable discussing the police being called and what that said about Johnson’s character, but what Grieve went on to say about the challenge facing the new prime minister was more damning.

Grieve pointed out that Johnson, if he wins, will take over a minority government. After the Tories lose the Brecon and Radnorshire by-election, they and the DUP will have a majority of three. Thus Johnson’s pledge to leave the EU, “deal or no deal”, on 31 October is not “in any way a realistic possibility”.

Grieve is right to point out that “a large number of Conservative MPs”, including Philip Hammond, the chancellor, and Ken Clarke, the former chancellor, are resolutely opposed to a no-deal Brexit and will make sure it does not happen.

Grieve made it clear that, if necessary, they would bring down any prime minister who “announces he is taking the country on a magical mystery tour towards a 31 October crash-out”. He pointed out that this would not necessarily lead to a general election, because the prime minister could simply be replaced by another Conservative who had what Grieve called “a tenable policy” – by which he meant one of going to the EU to ask for a further extension.

I doubt that it would come to that, because the threat of a vote of no confidence should be enough to persuade Prime Minister Johnson to ask for an extension himself. In any case, I think parliament would have legislated by then to require him to do so – as it showed itself capable of doing in April.

Johnson’s row with Carrie Symonds is unlikely to stop him becoming prime minister, and does not necessarily mean he would be bad at the job. What guarantees that he would not “survive very long” as prime minister, as Dominic Grieve put it, would be if he continued to pretend that he can take Britain out of the EU at the end of October, with or without a deal.