Boris Johnson has enjoyed the advantage, during his brief prime ministership, of being regarded by his critics as an inept negotiator whose efforts are doomed to failure.

At every twist and turn in the Brexit process, high-minded Remainers and their illustrious journals – one thinks of The Financial Times and The Guardian –  have done him the favour of placing the most unfavourable interpretation on his conduct, advancing with implacable confidence the gloomiest predictions of how things will play out.

Yet this week, opinion has turned in his favour. Suddenly a Brexit deal is said to be there for the taking.

For the avoidance of doubt, let me say I do not know for certain whether a deal will actually be done in Brussels, and then ratified at Westminster and elsewhere.

Nor do I contest the right of every freeborn Briton to place the lowest construction on whatever the Prime Minister of the day happens to be doing.

The occupant of 10 Downing Street performs the inescapable function of taking the blame when things go wrong, and Johnson too may end his days as the nation’s scapegoat.

But throughout the Brexit debate, a note of hysteria has been detectable in the forecasts of impending doom. Fanatical certitude has driven out honest doubt. Dreadful things which might happen at some future time have been treated, for polemical purposes, as if they have already occurred, or at least as if they have become inescapable.

There has been a failure to understand movement. The opposing forces in Brexit have been treated, by pessimistic commentators, as so fixed and rigid that agreement is impossible.

If this idea of politics were correct, nothing would ever change.

Paul Goodman suggested on Tuesday on this site that Leo Varadkar has become Johnson’s most important ally. This change from adversary, or impediment, to ally may at first sight seem surprising.

But on closer inspection, it is natural that London and Dublin should discover a common interest in reaching a sensible deal which is acceptable to people on both sides of the Irish border.

To reach that agreement requires a willingness to compromise, to see each other’s point of view and to make common cause.

But such enlightened liberality is not enough. It needed to be accompanied by a glance into the abyss: an appreciation of the severe consequences of not reaching a deal.

And that is why Johnson sought, in the face of much criticism, to set a time limit for these negotiations. Only then does the abyss, or cliff edge, become close enough to concentrate minds.

Theresa May tried the same approach, but with a brittle intransigence which failed to win friends and influence people. Johnson has been at once more robust, and less intransigeant.

He understands movement, can see when others may be ready to shift, knows a certain effrontery may be required, but also that he has to reassure people.

He believes the nearer he gets to attaining the great aim of Brexit, the harder it becomes for anyone to incur the odium of wrecking the talks, and the more the details fall into place – this latter an attitude which horrifies his pedantic detractors.

By being so scornful, they have set a low bar for him. We are about to see whether he can astonish them by bounding over it.