The exodus from Boris Johnson’s government has already begun

Alan Duncan, the Europe Minister, has quit the government ahead of Boris Johnson’s expected victory in the Conservative leadership election, telling Theresa May that he is unwilling to serve in a government led by the frontrunner.

Perhaps the only minister whose pre-emptive resignation comes as less of a surprise than that of Philip Hammond, Duncan – a supporter of Jeremy Hunt – was always destined to leave his ministerial post for an extended and possibly permanent stint on the backbenches one way or another.

Having served under Johnson at the Foreign Office, Duncan has since become one of his most vociferous critics, and last week accused the prospective prime minister of throwing Kim Darroch, the former US ambassador, “under the bus”. The enmity is mutual and there was precisely zero chance of Duncan keeping any government job in the event of a Johnson premiership.

Though opposed to leaving without an agreement, Duncan cannot really be said to be of a one with Philip Hammond, David Gauke and Margot James – three departing ministers opposed to no-deal – and was not part of the group of dissident ministers who repeatedly defied the whip in order to stop such an outcome. Though he swells an already growing number of malcontents on the backbenches, he is much less likely to take radical action to stop no-deal than some of his colleagues.

But that isn’t to say that Duncan’s resignation will cause no problems for Johnson. Rather, it throws the duff parliamentary hand he will inherit tomorrow into sharp relief. A substantial minority of his parliamentary party will be unreconciled and unreconcilable to both his central policy and the fact of his premiership. That would be difficult enough for a prime minister with a sustainable working majority. For one who will soon be hobbled with a majority of three, it is potentially fatal. And therein lies the problem: for Johnson, the case for a general election gets stronger with every resignation – but each departure also makes the job of getting Brexit done before going to the country ever more difficult.