Johnson is asked about another comment he's made in the past, when he was revealed to have said "F--- business" in response to opposition from business leaders to Brexit.

He says he has stood up for business throughout his career. "I will stick up for every business in this country," he says, before referencing his duties as Foreign Secretary. "You have to sell the UK abroad" in the role, and no-one would be a better salesman for the UK than him, Johnson says.

The final question returns to Brexit -- he is asked what he will do if Parliament cannot agree to his plan for Brexit, and if he will commit to resign if he cannot meet his own October 31 deadline for the UK's exit.

He replies that an "existential threat" faces both Conservative and Labour if they cannot pass Brexit, and that he does not expect lawmakers to "obstruct the will of the people."

"If we now block it ... we will reap the whirlwind, and we will face mortal retribution from the electorate."

"Let's come together and get this thing done," he says to colleagues in the House of Commons -- including those in the Labour Party that he attacked as Marxists a few minutes ago.

"There may be bumps in the road" on Brexit, he admits. But he swerves the question of whether he will resign if he can't follow through on his pledge -- a question which may well rear its head again should Johnson take the keys to Number 10.